Often we approach matchday six of the Champions League and find there is little to play for, with the groups all but decided. But not this time Ã¢ÂÂ there are plenty of knockout spots up for grabs, and some particularly exciting matches. In four of the eight groups, there are second v third contests, where the winner goes through and the loser is eliminated. The knockout stages have effectively arrived already.
ChelseaÃ¢ÂÂs key player in their crucial home match with Valencia is unquestionably Juan Mata Ã¢ÂÂ their best performer in SaturdayÃ¢ÂÂs 3-0 win over Newcastle, and up against the club he left in the summer.
MataÃ¢ÂÂs swift adjustment to English football has been highly impressive. He could have been forgiven for taking a while to adapt to the physicality of the league, but his intelligence and movement has compensated for his physical slightness, and heÃ¢ÂÂs established himself as a vital component of the side.
ItÃ¢ÂÂs in Europe, however, where he might be needed the most Ã¢ÂÂ Chelsea have never had that type of intelligent playmaker to open up packed defences, and this match is the first test to see whether he can elevate himself into the Kaka, Andres Iniesta or Wesley Sneijder figure he has the potential to be. ItÃ¢ÂÂs rare to see a side lift the European Cup without a player of that ilk.
In the first match at the Mestalla, Mata was fielded on the flank and generally stayed in wide positions. More recently, though, as the Newcastle game shows, heÃ¢ÂÂs been operating more centrally. Chelsea probably need him at the heart of the side to inflict maximum damage on his former employers, though Unai Emery will doubtless have a plan to stop him.
They may have expected to be through by now, but Manchester United find themselves having to get a result away in Switzerland. Basel are in good form, and are fresh from an important victory over fellow title challengers Lucerne at the weekend.
Two players United have to watch out for have very different qualities. Calm, intelligent 19-year-old midfielder Granit Xhaka, who made his international debut against England at Wembley in the summer, sets the tempo in midfield and broadly plays the role Michael Carrick did at his peak; mixing short unfussy passes with more searching balls to the flanks. Sir Alex Ferguson should opt to nullify him, perhaps asking Wayne Rooney to pick him up when Basel have the ball.
Veteran striker Marco Streller is an entirely different beast. 6ft5in and a good target man, his style is obvious from the passes he received in his previous game against Otelul Galati Ã¢ÂÂ generally long balls, often from the goalkeeper.
UnitedÃ¢ÂÂs recent defensive switch Ã¢ÂÂ playing Nemanja Vidic as the right-sided centre-back with Rio Ferdinand to his left Ã¢ÂÂ should work well here, with the aerial specialist Vidic likely to be up against Streller.
Joe ColeÃ¢ÂÂs move to French champions Lille has gone rather well Ã¢ÂÂ heÃ¢ÂÂs settled in the country, is seeing plenty of action, and has more license to express himself under Rudi Garcia than under Kenny Dalglish, Roy Hodgson or Carlo Ancelotti.
ColeÃ¢ÂÂs last game in England was in a 1-0 defeat to Aston Villa at the end of last season - coincidentally, Villa were the side he turned down to join Lille. In that match, he was used on the left of midfield and barely had an impact on the game, staying wide and completing only 16 passes before being removed midway through the second half.
At Lille heÃ¢ÂÂs much more involved Ã¢ÂÂ although he was fielded wide away at CSKA Moscow in their last match, he has more freedom to drift inside and link up with the other attacking players. A high proportion of his passes are played from a central playmaking zone, the position he believes he thrives in.
Cole will be important for Lille against Trabzonspor Ã¢ÂÂ if the French side win the game, and with Chelsea, Manchester United and Manchester City struggling, he might find himself one of very few Englishmen to be competing in the knockout stage.
Zenit and Porto battling for second place in Group G is not unexpected, but one would have predicted last yearÃ¢ÂÂs quarter-finalists Shakhtar Donetsk to have been the side already through, rather than Cypriot surprise packages APOEL.
This should be an exciting, frantic game. The sides have very different styles Ã¢ÂÂ Porto are proactive and like to press high up the pitch, Zenit are much more cautious and have a very large emphasis upon the counter-attack. Expect Porto to make the running, but Zenit to pounce when you least expect it.
As far as key players go, both Hulk and Roman Shirokov were important in the first meeting between these two, a 3-1 win to Zenit. Hulk is famous for his thunderbolt shots and fiery temper, but when he gets the ball in deep positions he uses it intelligently Ã¢ÂÂ he didnÃ¢ÂÂt misplace a single pass in the previous game.
Zenit play a very fluid midfield triangle of Shirokov, Igor Denisov and Konstantin Zyryanov. Shirokov often starts in deep positions before breaking into the box unmarked, and will need to be tracked by one of PortoÃ¢ÂÂs central midfielders Ã¢ÂÂ possibly Joao Moutinho.