Milan v Tottenham: Milan have been knocked out at this stage by an English team in each of their last two seasons in the competition and, given Tottenham's performance in their group stage matches against Inter, Harry Redknapp will feel his side has every chance of making it three.
Injuries are Redknapp's biggest concern with Gareth Bale and Luka Modric both major doubts for Tuesday's trip to the San Siro, while concerns persist over the fitness of other key performers such as Rafael van der Vaart (pictured). Tottenham are the joint-highest scorers from the group stages, with 18 goals in six games, but they also conceded 11, as many as any team who reached the last 16.
Tottenham's away form, in particular, looks suspect and the Serie A leaders will be looking to Zlatan Ibrahimovic, who has scored four goals in five games in the group stages, to do what he has often failed to do and make the difference against an English side in the Champions League.
Valencia v Schalke
Valencia found goals in easy supply in the group stages when they finished runners-up to Manchester United despite scoring more than twice as many goals as Alex Ferguson's side. Under Unai Emery, the Spaniards may lack some of the flair of previous years when the Davids, Villa and Silva, led their attack but in Joaquin and Juan Mata they have two probing attackers who can be devastating.
Schalke impressed in qualifying, winning a group that included Lyon and Benfica, and it is on their home ground where they excel. Inspired by a frontline of Raul, Klaas-Jan Huntelaar and Jefferson Farfan, they won all three games in the Veltins Arena convincingly and supplemented that with sturdy away displays.
Valencia have not beaten any of the three German sides to visit the Mestalla in the Champions League and that is something they may need to address on Tuesday if they are to reach the quarter-final.
Arsenal v Barcelona
Given the mauling Arsenal suffered at the hands of Barcelona in last season's quarter-final, the draw that again pitted Arsene Wenger's side against the La Liga champions was a bit like telling a man suffering from post-war syndrome that he has to go back to the front line.
The very sight of Lionel Messi (pictured), who scored all four in the 4-1 second leg win at the Nou Camp last April, could be enough to send several Arsenal players scuttling back to the dressing room. And you could hardly blame them as the Argentinean has 37 goals from the 31 appearances he's made for his club this season.
Wenger's biggest problems, however, will invariably come from his own side. Samir Nasri has been their best player this season but he is likely to miss out through injury. As usual, it is Wenger's defence which looks the most fragile, and the suspension of Bacary Sagna will not help. Thomas Vermaelen could return for the second leg to provide some stability. They may need it.
Roma v Shakhtar
It's hard to envisage a set of circumstances that will see anything but progression to the last-eight for the Italians, but then Roma can be their own worst enemy when expectation levels are high.
Shakhtar have lost all six European games they have played in Italy, conceding four or more in each of the last four, and are further hampered by not having played a competitive game since their win over Braga in the group stage back in December.
There are goals in their side, however, with the Brazilians Luiz Adriano and Douglas Costa along with former Arsenal striker Eduardo helping them to top spot in their group.
Claudio Ranieri's Roma are the only one of the 16 teams left who have yet to keep a clean sheet in the competition, but their home form is strong and Marco Borriello and Adriano can trouble any side, while Danielle De Rossi has been one of the most accomplished midfielders of the competition so far.
-- Evan Fanning