Inter Milan (2nd to Tottenham in Group A)
The defending champions are struggling enormously this season under the great man Rafa Benitez, and there's no guarantee that they'll get close to winning anything this season. Rumoured to be on his way to Old Trafford last summer, Wesley Sneijder is certainly their most damaging player, whilst strikers Diego Milito and Samuel Eto'o could also cause our defence some headaches.
A Round of 16 tie against Inter would be by no means easy, however it's safe to say that we'd go in to the tie as favourites based on form. Our performance last time around at the San Siro (against AC Milan in February this year) also shows that we're more than capable of performing there. Preferably we'd avoid them as they are still a top quality team, but if we drew against them it wouldn't be the end of the world.
Olympique Lyonnais (2nd to Schalke in Group B)
A club whose best players can be found in its midfield, Lyon finished a predictable 2nd in their group behind German giants FC Schalke. Lyon notched up 3 wins in their first 3 group matches, before taking their foot off the throttle and qualifying second after 2 losses and a draw in the second half of the group stage. A tie against Lyon would be a challenge, however we would again definitely go in as favourites, given that we are undefeated this season, and that we have the superior squad.
FC Kobenhavn (2nd to Barcelona in Group D)
To be honest, Kobenhavn would probably be the easiest of the 2nd placed clubs to play against, given that they have qualified 2nd out of a relatively easy group (besides Barcelona of course). They don't seem to pose too much of a threat to us, and I'd say it would take a massive upset if they were to knock us out of the competition.
AS Roma (will probably finish 2nd to Bayern Munich in Group E)
Our 7-1 smashing of them in the 06/07 campaign will always be remembered fondly by United fans, although it's hard to see that happening again should we draw them. However, although Francesco Totti, Daniele De Rossi and Marco Borriello are all top notch players, the rest of the squad lacks talent and depth, and for that reason United should be able to get the job done against them.
Marseille (finished 2nd to Chelsea in Group F)
Their squad boasts ex-United defender Gabriel Heinze, and they've won their past 3 Champions League fixtures, although that could change as they face Chelsea tonight. In comparison to the likes of AC Milan, AS Roma and Inter, they're probably not as tough an opponent, as is shown in the fact that Chelsea were able to beat them 2-0 without Drogba. Certainly wouldn't be dissapointed if we draw them.
AC Milan (finished 2nd to Real Madrid in Group G)
Of the 6 possible teams we could draw (assuming Arsenal finish 2nd in Group H), AC Milan would probably be the toughest opponent. Sitting atop the Serie A table, and having performed reasonably well in a tough group, midfield whiz Ronaldinho may cause us similar sorts of problems as he did last time around, even though we managed to beat them fairly convincingly overall.
Even though we should be able to beat them if we draw them, there's still an element of doubt, coming up against them again, this time with an out-of-form Wayne Rooney. It's probably best to avoid them, even though it's most likely that we'd be the ones progressing to the quarter finals.
This list has been compiled assuming that Arsenal will finish 2nd in Group H, and has not included them or Valencia because we are ineligible to play against either of them in the Round of 16. As they would have been our two toughest possible opponents, it's a good thing that we're certain to avoid them. Obviously, Sporting Braga and Shaktar Donetsk could also finish 2nd in Group H, but the most likely result is for Arsenal to finish 2nd, with Shaktar in 1st.
Whilst we should be able to defeat whoever we are drawn to play against in the Round of 16, it would obviously make our task a lot easier if we're drawn against a team such as Kobenhavn or Marseille than against a team like Inter or AC Milan. I guess from now the focus switches to both the Premier League and the FA Cup until the Champions League resumes on February 15.