Sir Alex Ferguson is aiming for a third Champions League win with Manchester United
Manchester United will learn their opponents in the last 16 of the Champions League when the draw is
United qualified from their group with two games to spare after failing to progress to the knockout stages last season.
Here we look at the opponents Sir Alex Ferguson’s side could face in the first knockout stage of the tournament.
Lucho Gonzalez has been an influential figure for Porto this season
FC Porto missed out on qualification for the knockout stages last season but struck back this term by progressing with two games remaining, just as Manchester United did.
Midfielder Lucho Gonzalez, after returning to Porto following three years at Olympique Marseille, was instrumental in Porto becoming the first team to reach the knockout stages and scored in the opening Group A win over Dinamo Zagreb following the death of his father hours before the game.
Porto, under Jose Mourinho, knocked United out of the Champions League in 2004.
Stephan El Shaarawy has been a revelation for AC Milan this season
Stephan El Shaarawy, 20, has become a fan favourite for his performances since scoring in the win against Zenit, as he spearheads a new generation of Milan players, including Mattia De Sciglio and Bojan Krkic.
Real Madrid's Cristiano Ronaldo played for Sir Alex Ferguson at Manchester United
The Portuguese international represents the main danger for Real but Karim Benzema, Xabi Alonso, Luka Modric and Mesut Ozil will also pose a threat.
United have never beaten Real in the Champions League, losing both previous ties against the Spanish giants.
Willian helped Shakhtar Donetsk reach the Champions League knockout stage
The Brazilian influence of Willian and Fernandinho has helped Shakhtar Donetsk reach the Champions League knockout stage for only the second time.
The Ukraine side looked comfortable in the early stages of Group E, but missed out on the top spot when they lost at home to Juventus in their final game.
United have never played Shakhtar before in any European competition.
Jonas has scored four times for Valencia in the Champions League this season
Valencia have looked solid in the Champions League but inconsistent in La Liga this season.
Brazilian Jonas has played a starring role for the Spanish club with four goals in Group F, but Roberto Soldado and Sofiane Feghouli have also impressed.
Valencia knocked United out of the Champions League in the first knockout round in 2001.
Goalkeeper Fraser Forster helped Celtic defeat Barcelona in the Champions League group stage
Celtic caused the shock of the group stages when they defeated Barcelona at Parkhead but their 3-2 win at Spartak Moscow built the momentum for progress out of Group G.
Goalkeeper Fraser Forster was a colossus in the win over Barca, while midfielder Victor Wanyama is rated highly at the club.
United have only played against Celtic in the group stages, winning two matches, losing once and drawing the other.