Daniel Ricciardo and Daniil Kvyat will once again battle for supremacy within Red Bull when the 2016 Formula One season kicks off in March—and both will be hoping for a better year than the one just gone.
While the Mercedes engine remained the class of the field and Ferrari made huge strides with their own power unit, Renault continued to struggle. The result was another difficult season for Red Bull.
Despite having one of the best chassis—as proved in the wet at the United States Grand Prix—Ricciardo and Kvyat managed just three podium finishes between them. Red Bull, overtaken by both Ferrari and Williams, fell from second in the 2014 constructors' championship to fourth in 2015.
But there were a few rays of sunshine poking through the gathering clouds over Milton Keynes. Ricciardo remained on top of his game and came close to winning two races, while Kvyat performed admirably in only his second season of F1 racing.
Red Bull will continue with Renault engines in 2016, so a title challenge is highly unlikely. The two drivers will therefore have more time to think about the most important battle for any racing driver—the fight against his team-mate.
Ricciardo established himself as one of the sport's top drivers following his comprehensive defeat of Sebastian Vettel in 2014.
The Australian was always in place to pick up the pieces whenever Mercedes dropped the ball, and victories at the Canadian, Hungarian and Belgian grands prix were his rewards.
Though an impressive all-rounder, it was his overtaking ability that really caught the eye and marked him out as something very special. His move on Vettel at the Italian Grand Prix was just one of the many stunning and often key moves Ricciardo pulled off throughout the year.
Kvyat arrived to partner Ricciardo at least one year earlier than Red Bull might have hoped. Vettel's decision to jump ship to Ferrari left the Austrian team with a seat to fill, and the young Russian was deemed the strongest prospect in the team's "reserves."
The statistics disagreed with this assessment; across 19 races in 2014, Kvyat was outscored 22 points to eight by Toro Rosso team-mate Jean-Eric Vergne.
However, the points gap was in no way representative of a much tighter on-track battle, and Vergne had the benefit of two extra seasons of F1 experience.
Furthermore, Kvyat had proved he had exceptional raw speed—the consistency that racks up points finishes often comes later for youngsters.
But there was one truth hidden in their points tallies—Vergne looked the more "finished" driver at the time. Kvyat was still very much a work in progress, chosen for the future; for him, 2015 would be as much about finishing his apprenticeship as it would be about establishing himself as a top talent.
It therefore went without saying that Ricciardo was the heavy favourite to emerge as the top Red Bull driver.
The start of the 2015 season went much as many fans would have expected, at least so far as the battle between the two Red Bulls was concerned. Ricciardo outqualified Kvyat four times in the opening five races, reaching Q3 on every occasion.
The Australian made the most of this good one-lap form to score points at every one of these races.
Kvyat didn't look entirely at home in the RB11, missing out on Q3 three times in this period, and his start to the year wasn't helped by a few reliability issues. He didn't even make it to the grid in Melbourne after his car broke down on the lap to the grid, and in China his engine failed well before half distance.
But it would still be fair to say he wasn't really getting the job done, and after Toro Rosso rookie Carlos Sainz Jr. overtook him to snatch ninth at the Spanish Grand Prix, Red Bull advisor Helmut Marko issued a very public wake-up call.
Marko told Kleine Zeitung (h/t Motorsport.com), "Our established guys need to look out. Paradoxically, the more inexperienced ones did the better job."
Kvyat's season finally got going at the sixth round, Monaco. Though Ricciardo outqualified him for the fifth time, the Russian got a better start and took fourth from his team-mate into the first corner.
The two Mercedes and Vettel's Ferrari were too quick, but Kvyat was more than comfortable as the best of the rest, and he finished fourth to pick up 12 points for what was, at the time, the best result of his F1 career.
Perhaps spurred on by this success, Kvyat outqualified Ricciardo at three of the next four races and outscored him in two of them. It was clear that the 21-year-old was finding his feet at the team and starting to push closer to his potential; Ricciardo, after dominating the early stages, had a real fight on his hands.
The Hungarian Grand Prix offered both Red Bulls a chance to score good points. The tight, slow Hungaroring circuit suited the RB11, and initially Ricciardo looked the most likely to secure a podium finish after Lewis Hamilton's errors and Kimi Raikkonen's retirement.
He was clearly quicker than Kvyat that weekend, and when a late safety car bunched up the field, there was even a chance he might grab the win.
However, an unfortunate series of events saw his hopes evaporate. Ricciardo's car sustained damage after he was hit by Hamilton while overtaking, but he was still able to catch the other Silver Arrow of Nico Rosberg.
Ricciardo sat behind for a number of laps before attempting a huge outbraking manoeuvre, but he ran wide. Rosberg drifted across to seize the racing line, and the two touched, destroying the Red Bull's front wing and puncturing the Mercedes' tyre.
Both were forced to pit, and though Ricciardo was still able to salvage a podium, it was Kvyat who came home in second to record his and the team's best result of the season.
After 10 races, the two Red Bull men were separated by just six points in the drivers' standings. Ricciardo led the way with 51, but Kvyat was close behind on 45. The qualifying battle stood at 6-4 in Ricciardo's favour, while in the seven races in which both had finished, Kvyat had been ahead four times.
But the statistics did not necessarily reflect accurately on what had happened on the track—Ricciardo had been more than six points better than Kvyat.
The second half of the season started in much the same fashion at the first, at least with regards to qualifying. Ricciardo started ahead four times in the five races from Belgium to Russia, but luck was rarely on his side.
He might have been on the podium at Spa had his car not broken down, a suspension failure robbed him of a likely fourth-place finish at Sochi and a first-lap collision with Felipe Massa ended his hopes of points in Suzuka.
But amid the misfortune came the Australian's best result of the year, second at the Singapore Grand Prix.
Ricciardo kept Vettel's victorious Ferrari within sight for the entire race and later told press, including ESPN's Nate Saunders, that he felt he might have been able to win had the safety cars not emerged when they did.
Kvyat was a lowly sixth at Marina Bay after some appalling misfortune with the safety cars. However, Lady Luck was more often than not on his side, and he benefited more than once from his team-mate's failures.
With four races to go, Kvyat had his nose ahead in the drivers' standings with 76 points to Ricciardo's 73.
Neither man enjoyed the United States Grand Prix, despite both challenging for the lead in the early stages; Kvyat crashed out on the damp track, and Ricciardo fell back to 10th after being hit by Nico Hulkenberg and Sainz Jr.
But Mexico was a happier hunting ground for the pair—and the scene of Kvyat's best drive of the season. With both Ferraris playing "hunt the barrier," the Russian looked set for an excellent podium, before a safety car gave Valtteri Bottas the opportunity to overtake.
The duo then traded "wins" in the final two races, Kvyat on top in Brazil and Ricciardo ahead at the season-closing Abu Dhabi Grand Prix. With each taking 19 points from the final four rounds, Kvyat retained his lead in the intra-team points battle.
For the second year in a row at Red Bull, the newcomer had beaten the old hand.
The final points table did not accurately reflect on reality. Kvyat was not the best or the quickest driver of the two over the course of the year—Ricciardo was.
The prevailing view among observers was that the Australian had very much held the upper hand—Autosport's Ben Anderson rated Ricciardo as the fourth-best driver of the year (and Kvyat the 14th-best), while F1 Fanatic's Keith Collantine placed Ricciardo in fifth and Kvyat in 10th.
But Kvyat had just 19 grand prix starts to his name prior to the season start, and he was thrust into a high-pressure role at one of the top teams, alongside one of the best drivers around, at least one year too early.
And at the end of the year, he was still just 21 years of age.
Taking these things into account, there is no denying that Kvyat did a fantastic job in 2015, and this was reflected in his placing of fifth in the Autosport team principals' top 10 rankings.
In an ideal world, Kvyat would enter 2016 with a bit of job security, looking to polish off the final rough edges and transform himself into a true top driver. But instead, he'll be hitting the track knowing that the only way he can guarantee himself a Red Bull seat in 2017 is if he can genuinely outperform Ricciardo.
The greatest threat to Kvyat's future with the team is Max Verstappen. If the Dutchman has another excellent season and continues to come across as a true once-in-a-generation talent, Red Bull will not hesitate to give one of their current drivers the boot to make space for him.
Sainz Jr. is also a threat—if he turns the tables on Verstappen and stands out as the team's top prospect, Red Bull will find space for him.
If the decision had to be made today, it would be an easy one for the team. Ricciardo has proved himself to be one of the top four or five drivers in F1 today; Kvyat has not. The Russian would be the man to make way.
So in 2016, Kvyat needs to do what Ricciardo did in his own third season—he has to establish himself as one of the true stars of tomorrow. To do this, he must prove to the Red Bull management that he is at the very least Ricciardo's equal.
That means not only beating him the points table, but also doing it on the track. Anything less, and—ridiculous as it sounds—he'll probably find himself looking for a new team as the season nears its end.
Kvyat is more than good enough to find one, but he'd probably prefer to stay where he is.
Ricciardo is not quite under the same sort of pressure as Kvyat, because his performances in 2014 and 2015 earned him a place close to the elite trio of Fernando Alonso, Hamilton and Vettel.
Speaking to this writer in October, Hamilton indicated he considered Ricciardo as the next in line behind his fellow multiple champions in the race to be the best, and there is no greater praise than that of your rivals.
But that was then, and it doesn't matter how good a driver is if someone else turns out to be even better. If Kvyat starts beating him regularly and Red Bull see the Russian as their future, Ricciardo will be the man under threat from the Toro Rosso stars.
If the axe falls, he'll have options with other teams—but will any of them be better than Red Bull?
The four-way battle between the Red Bull and Toro Rosso drivers probably won't produce any race-winners, but it'll still be one of the highlights of the year.