As one of the landmark fixtures in this season's Champions League round of 16, Manchester City will host Barcelona in February before returning to the Camp Nou in March, hoping to extend their European run.
Manuel Pellegrini has already led the English giants past the competition's group stage for the first time in their history, but their lack of European pedigree will get a stiff examination when the Chilean is reunited with his old La Liga rivals.
Boasting two of the most fearsome squads in all of club football, there are blockbuster battles all over the pitch in this encounter, but I've picked out the top three.
Sergio Aguero vs. Gerard Pique
Having just been ruled out for the remainder of 2013, Sergio Aguero is one player who will likely still be on the comeback trail by the time February's Barca matchup comes knocking.
Sky Sports confirmed the recent blow to City's squad:
Manchester City's Sergio Aguero ruled out for at least one month with calf injury #SN— Sky Sports News (@SkySportsNews) December 16, 2013
If Aguero does stick to the one-month predicted absence—therefore proving his fitness in time for the first leg—he will almost certainly be a guaranteed starter for Pellegrini's men.
Former Manchester United youngster Gerard Pique is likely to be the man charged by Gerardo Martino with stopping the Argentinian, who has netted 13 league goals this season.
The back four (sometimes three) hasn't been among Barca's strongest aspects this term, with set pieces a true Achilles' heel, as seen by Villarreal's equaliser at the weekend. Aguero's movement makes him dangerous at all times, but it was his anticipation at a corner against Arsenal that got City moving on Saturday.
Given the kind of form Aguero has been in this term—he's scored 19 goals and made 10 assists in 19 starts across all competitions, per Transfermarkt.co.uk—the Citizens know they have the firepower to exploit the Barcelona defence. Alvaro Negredo, David Silva, Yaya Toure and Samir Nasri are all capable of hurting opposition back lines.
However, as a man-for-man battle, few defenders are as well-equipped as Pique to handle Aguero. The Barca man has pace and agility in abundance, reads the game superbly and the Spain international is part of a Catalan-led defence that has conceded only 10 league goals in 16 outings this term.
Yaya Toure vs. Sergio Busquets
In terms of the complete midfielder, Yaya Toure and Sergio Busquets are two names who must be discussed among the world's finest of their trade.
Totally different in style, Busquets retains possession as well as anybody while shielding his back four, while Toure injects power, directness and no little class into City's engine room.
Both will want to be on the front foot in this tie. If Busquets is in control, he will be sat inside the centre circle just inside City's half, prompting Barcelona attacks. If Toure is calling the shots, Busquets will be covering far more ground than he wishes.
Toure's attacking qualities have grown far beyond anything ever managed during his days at the Camp Nou, and the Ivorian's assets going forward will be needed if Pellegrini's men are to move past their Catalan counterparts.
City will not out-pass Barcelona in a tactical chess match, but if Toure drives his team forward he can single-handedly ruin Barca's rhythm.
Vincent Kompany vs. Lionel Messi
Based on how Pellegrini's side are currently lining, it's likely that Fernandinho will also have a big say in how this particular battle opens up, but Vincent Kompany will attempt to play the role of Lionel Messi's tormentor for the most part.
Who advances to the Champions League quarter-finals?
Europe is awaiting Messi's 2014 return to fitness with bated breath, and the earlier in January that the Argentinian makes his comeback, the more time he'll have to settle into a groove in time for this two-legged fracas.
Kompany has been, and remains, his club's strongest and most consistent defensive outlet, and communication with those around will be crucial in taking care of one of the sport's biggest attacking threats.
An injury-prone 2013 will be considered one of Messi's more forgettable, but a winning turnout against the Citizens will be vital if the 26-year-old is to stage a better performance in 2014.
Kompany should look to force Messi to play the ball wide, knowing Barcelona hate to throw balls into the box unless it's a last resort.
Prediction: Manchester City 3-2 Barcelona; Barcelona 2-2 Manchester City (5-4 on aggregate, Manchester City advance).