Three critical European matches kick off Wednesday as the first leg of the knockout round of the Champions League wraps up. Bayern Munich travel to Swiss champions Basel , while Inter Milan look to find their stride at Marseille .

But the biggest game of the day may be in Manchester (and in another competition entirely). There, Premier League-leading Manchester City host Portuguese champions Porto in the return leg of their Europa League knockout round tie , the English side holding a 2-1 lead.

City hold all the cards: a one-goal lead, two away goals (if needed for the tie-breaker), and no new injury concerns. They are likely to field a nearly identical lineup to the one that was selected last week in Portugal, though Sergio Aguero will probably get the starting nod over Mario Balotelli. Aguero's winner was the difference last time in a game that was rarely pretty and littered with cards. City picked up six yellows on the night and can be fairly said to have won ugly.

Midfield general Yaya Toure proved to be the difference on the night, slotting right into the lineup despite having played just four days prior in Cote d'Ivoire's loss on penalties to Zambia in the African Cup of Nations final. It was his passing that forced both goals and his spirit that rallied a team that looked lethargic throughout the first half. Balotelli was not a factor for much of the evening, and had David Silva not enjoyed another one of his splendid outings, Porto would have walked off with the win.

Porto have both absences and history to contend with. They will be without wingback Danilo (knee, injured in a tackle with Yaya Toure) and Chelsea target Alvaro Pereira, who is suspended. Pereira helped City erase Porto's lead by heading the ball past goalkeeper Helton and into his own net last time out, but he also was the spark that set up Porto's opener, running an effective game with James Rodriguez and Joao Moutinho. More troubling, Porto have never won in England, coming closest when Jose Mourinho guided them to a 1-1 draw at Old Trafford, eliminating Manchester United en route to the 2004 Champions League title.

But Porto are a quality side, and if anyone thinks this will be a cakewalk for City, they are wrong. Hulk lived up to his name last time, proving to be far too much for Nigel de Jong to handle. If Helton enjoys another superb game in the nets and Hulk shows the fire and flair he did last time out, this could be a real battle.

Hanging over the game is an investigation into alleged racial abuse of Yaya Toure and Balotelli by the fans at the Estadio do Dragao . City have reported that the two players were subjected to racial taunts from the stands, and UEFA is expected to act shortly on the matter . Porto has denied the accusations, saying that the fans were instead chanting in support of Hulk and against Aguero.

There is one historical note in Porto's favor: They have a superb record in two-legged ties in the Europa League and the old UEFA Cup, not having lost one since 2001.

The winner of Wednesday's match will face the winner of the Legia-Sporting Lisbon match in the round of 16. Sporting hold two away goals after a 2-2 draw in Poland last week.

Our two Champions League games lack the name value on offer at Eastlands. Bayern Munich are favorites over minnows Basel, and Marseille's meeting with Inter could be a real slog.

Bayern have slipped in the Bundesliga but remain in the hunt for title. That's not good enough for the Bavarians, however, who historically overreact to even the slightest of slip-ups. Still, in 2012, Bayern have only won two of their five league games and have conceded top slot after ruling the league at Christmas. They are eager to turn the page , and Basel may be the team they take their frustration on.

Basel, of course, shocked everyone by making it this far. They knocked Manchester United out and have the talent to cause problems. Indeed, Bayern took note and packed midfielder Xherdan Shaqiri in a $15 million transfer this winter. Shaqiri will finish out the season with Basel and will line up against his future club.

The man Shaqiri may well replace some day, Bastian Schweinsteiger, will miss the game after tearing ankle ligaments. Daniel van Buyten (foot) is also out for the match, and Thomas Mueller is expected to start out wide over Arjen Robben, as the oft-injured and under-performing Dutchman seems to be running out of rope at the club. Thankfully for Bayern, Franck Ribery will be there to pull the strings alongside Toni Kroos, with Mario Gomez lining up at Yann Sommer's net.

Basel have Marco Streller and the ageless Alexander Frei to run at Bayern, and as Manchester United manager Sir Alex Ferguson knows, those two can hurt you. But one has to feel their time in Europe is running out. They do not possess the depth or experience at this level, and Bayern are expected to advance, perhaps not without some effort.

In the day's other match, Inter Milan have been so erratic this season that even their most die-hard fans cannot be sure which side will show up. Inter have lost their last two league matches in embarrassing fashion , drooping against a poor Novara side then getting blown out by Bologna. Inter have no chance of winning the scudetto and are already out of the Coppa Italia. Indeed, they may face a fight just to qualify for European play next season. They look like a team that is coming apart at the seams, and the pressure is unlikely to ease on Claudio Ranieri any time soon .

Wesley Sneijder has been bouncing in and out of the lineup due to fitness concerns and has not been the presence of years past. One boost for the Italians is that Diego Forlan will finally get to join the competition, after he was ineligible for the group stages. Inter badly needs goals: Diego Milito is the only Inter player to have found the net in their last six games, and unfortunately those goals all came in a single match. Inter's defense hasn't helped either, as they've coughed up 15 goals in that same stretch, and once-dominant players like Lucio and Maicon have suffered dips in form.

Marseille are currently coasting in France, where they have put together a 15-game unbeaten streak. That's not enough for the title -- PSG and Montpellier have opened a wide gap over all others -- but they enter the game looking sharp. Mathieu Valbuena and Loic Remy have been excellent up top, though Remy's absence (thigh) could be a factor Wednesday. Fortunately, OM will get midfield anchor Alou Diarra back after the toe injury he suffered was judged not to be serious. Andre Ayew and his brother Jordan, are also expected to start after their African Cup of Nations run with Ghana.