The Champions League has now been whittled down to Europe's elite 16 sides, all vying for a place in May's final at Lisbon's Estadio da Luz.
Here, we take a look at some of the players likely to prove vital to their teams progressing to the quarter-finals.
Diego Costa, Atletico Madrid
The Brazilian striker has struck 26 goals in 35 games for Los Colchoneros this term, and it's difficult to see any hope for AC Milan against Atletico.
Add to that the fact Costa will be facing a Milan side struggling in 10th position in Serie A. I Rossoneri couldn't come at a better time.
Having been in formidable form this season, Costa sits only one behind Cristiano Ronaldo in the La Liga scoring charts on 21 goals.
It would be a brave man who bets against him adding to his tally against Milan.
Mario Mandzukic, Bayern Munich
Mandzukic has been in ruthless form for Bayern this term. As per ESPN.com, he has hit 12 goals and two assists in 19 games.
Although they will miss the creative talents of Franck Ribery, Arjen Robben will provide the creative spark needed to feed the goal threat that Mandzukic brings.
Pep Guardiola has long been an advocate of the "false nine" role, a role Mandzukic is not naturally accustomed to. Nevertheless, the former-Wolfsburg man has been in such dependable form this season that Guardiola has been willing to dispense with that philosophy for the goals he brings.
Arsenal's defence, led by Per Mertesacker will have to be on excellent form if they are to nullify the threat Mandzukic poses.
Much has been made of the big-money signings Manchester City have made since the Sheikh Mansour takeover. But it is often forgotten that Vincent Kompany, arguably City's best player in that period, was there before the money rolled in.
Kompany has been at the fulcrum of a City side that has conquered the English game and now will attempt to dominate Europe. If City are to progress, Kompany will be vital to repel the pressure exerted by Barcelona's mesmeric style of play.
Alan Brazil of TalkSport tweeted that Kompany was confident heading into the clash against the Catalan giants:
Exclusive - Kompany: Man City confident ahead of Barcelona Champions League test http://t.co/vpIbIKPjCX— Alan Brazil (@sportsbreakfast) January 10, 2014
Kompany has come to represent the virtues the Premier League seeks to extol. He is brave, fast and ferocious in the tackle. But it will be his reading of the game that will be most keenly tested against Barcelona.
Count on Kompany to shepherd City into the quarter-finals.