Barcelona continue their quest to win back Europe's most coveted club trophy in the new year when the knockout phase of the Champions League kicks off on the 20th of February.
Barcelona can move forward without fear of any club, but with a wealth of quality in this year's competition, they would be wise not to take their potential opponents lightly.
From seasoned European powerhouses Milan to perennial overachievers Porto, the Blaugrana could face a difficult test right off the bat in the first knockout round.
Let's take a closer look at Barcelona's five potential matchups.
Arsenal are a side that will give the Blaugrana few surprises, having been dispatched by the Catalan giants in the knockout rounds of 2010 and 2011.
Arsenal's form has been anything but convincing of late, dropping points in the league with worrying consistency and failing to impress anyone of their quality even when they win all three.
Jack Wilshere was one of Arsenal's best players two years ago at the Camp Nou, and he recently returned to full match fitness after a year-long injury absence.
Santi Cazorla, the Spanish playmaker and summer transfer, has been Arsenal's main attacking threat this season, with Olivier Giroud, Lukas Podolski and Theo Walcott all struggling to find consistency in their form.
Alex Oxlade-Chamberlain has recently been given a run in the side, and he could be a dangerous wild card down the right, running at an exuberant—but never eager to defend—Jordi Alba, should he get the chance.
Arsenal have long been compared to Barcelona in their style and outlook on the game, but without a major trophy since 2005, they've been unable to produce the same success to match their style.
The two recent ties required impressive performances by Barcelona in the return legs at the Camp Nou, with Arsenal leading for a time in each. This year's Arsenal team, though, may be their weakest in a decade and a half and shouldn't give the Blaugrana too much to worry about.
Porto came through a relatively weak group, settling for second place after a final match-day defeat at the hands of PSG.
With only four points dropped in the Portuguese Liga and only six goals conceded on the domestic front, they are well poised to make another Champions League surprise.
Porto feature a pair of Colombians for attacking options, with the Martinez and Rodriguez duo leading the way with ten and seven goals on the season to date.
Another side that like to play intricate football, Porto might be in some trouble when forced to defend against Barcelona. Their midfield three would struggle to deal with Barcelona's possession and pressure combination, and like Arsenal, I don't see them posing much of a threat in a two-legged tie.
Milan come into the Champions League knockout phase with plenty of history, but this year's team doesn't have the quality we've come to expect from the storied Italian side.
Sitting just seventh in the Italian League, the Rossoneri have struggled, especially on the defensive end, conceding fourteen goals in their eight away fixtures in Seria A.
Numbers like these, as well as the memories of their near collapse at the Emirates last season, will have Messi and Co. licking their chops in anticipation.
Though they've struggled to find a replacement for the personality and presence of Zlatan Ibrahimovic, Milan can call on the impressive goalscoring form of the young Stephan El-Shaarawy, who has scored 15 goals in just 23 appearances this campaign.
Milan will further hope that their Brazilian duo of Robinho and Pato can overcome their injury woes and supplement the threat going forward.
Bojan would love to get the chance to show his old side what he's worth, but with only the single goal on the season, he has yet to find his feet in his new home in Italy.
Overall, they will be looking to find some consistency in the months before the knockout phase begins; if they don't, Barcelona could make quick work of them.
The Turkish Champions finished group play level on points with CFR Cluj and progress to the knockout rounds courtesy of their head-to-head advantage over the Romanians.
Galatasaray are a gritty, experienced side that would most likely sit back and allow Barcelona to dictate the pace of play, taking their chances on the counter.
That being said, they certainly gave Manchester United a scare in Matchday 1, hitting the woodwork twice in a narrow 1-0 defeat at Old Trafford.
Featuring Umut Bulut and Burak Yilmaz in attack, Galatasaray also have the experience of seasoned veterans like Brazil international and ex-Juventus midfielder Felipe Melo and ex-Munich and Madrid player Hamit Altintop, among others.
Galatasaray could surprise Barca if they bring the same spirit and belief to the Camp Nou that they mustered at Old Trafford. But with their quality, of course, Barcelona should be able to win out in the end.
Of all the second place teams, none played a more impressive—and perhaps surprising—set of group stage fixtures than Shakhtar Donetsk.
After winning just one game in last year's competition, the Ukrainian Champions looked a formidable outfit against European Champions Chelsea and only narrowly missed out on first place in the group after a 1-0 defeat on the final match-day at the hands of Juventus.
With rising Brazilian stars Fernandinho and Willian taking the reins in midfield and attack, Shakhtar combine passes impressively and look one of the most creative sides in the competition going forward.
A round-of-16 tie between Barcelona and Shakhtar would be a neutral's dream, with the skillful Donetsk side unlikely to sit back and defend as so many teams are content—or forced—to do against the Blaugrana.
The big question for Shakhtar is whether they can hold on to their brilliant Brazilians, with transfer rumors consistently linking the pair with a host of English clubs. Without them, Shakhtar would be forced to play a much more conventional—and less successful—tie with Barcelona.
Not surprisingly, I see Barcelona as the strong favorites to reach the quarterfinals no matter their opponent, but for me, Arsenal are currently the weakest team of the five and Shakhtar the most worrisome.
Then again, a lot can change in two months in the world of football. Which side would give Barcelona the most trouble in the round of 16? Have your say below.