Madrid, Barca still slight favorites but have much to do in second leg

Here are seven observations from the first round of skirmishes where Bayern beat Madrid 2-1 and Chelsea edged Barcelona 1-0:

Real Madrid have a fullback problem

Bayern Munich is strongest on the wings, Real Madrid knew that. But it was still surprising to see the "Merengues" struggle so much to contain the Bavarians in the wide positions. Part of the problem actually lay in the center, where Xabi Alonso and Sami Khedira did too little to double-up on the flanks defensively. But you'd still expect the Spaniards' fullbacks to cope much better than they did at the Allianz Arena. World Cup winner Alvaro Arbeloa never got to grips with the mercurial Frank Ribéry on Tuesday while ?30 million ($39M) import Fábio Coentrão was continually embarrassed by Bayern's marauding right back Philipp Lahm. Madrid tabloid Marca wrote acidly that Benfica's president should get a statute after off-loading the left back for so much money. The only noteworthy involvement of substitute Marcelo, Coentrão's rival for the position on the left of the back four, was a late tackle on Thomas Müller that would have warranted a straight red card. The Brazilian, too, looks defensively suspect. The matter is complicated by dressing room politics. Coentrão shares an agent with José Mourinho and is rumored to receive preferential treatment, Marcello is said to be so unhappy with the situation that some suspected his foul on Müller amounted to an attempt to rule himself out of the return leg. It's not easy to see how the situation can be resolved ahead of the Clásico on Saturday night.

Not everything is quite what it seems at Bayern

Mario Gomez's late goal has changed the complexion of the tie and served as timely reminder of Bayern's mental toughness. But the Bavarians' much-feared psychological strength is more fragile than it seems. This season, they've recovered only once after going behind, a tendency that doesn't bode well for next Wednesday's trip to the Bernabeu. In addition, a very public disagreement between Arjen Robben and Ribéry over the right to take a free kick revealed a considerable amount of dressing-room tension. Even the last-minute win couldn't placate the Frenchman. Sport-Bild reported that Ribéry continued the argument more forcefully in the changing room after the final whistle; teammates had to separate the two by force. The board ordered both players in for a dressing down on Wednesday but decided to bury the incident for fear of upsetting either party. One or two early goals from Madrid in the second leg could well bring those tensions out in the open again.

Dani Alves needs to up his game

The Brazilian right back was kept quiet due to some heroics from Ashley Cole, Chelsea's best performer at Stamford Bridge, and was caught badly out of position for the Drogba's goal. Alexis Sanchez needs better support in the second leg; Alves' failure to make any telling forays forward contributed to Barcelona getting clogged down in the middle. For all his natural talent, Alves also needs to improve his decision-making. The fact that his left-back colleague Adriano looked the more dangerous fullback as the game progressed didn't reflect well on him.

Chelsea's limitations can be a virtue

In the Premier League, Chelsea is obviously a team in transition, seemingly undecided whether it should develop a more possession-based style of play, with Juan Mata as its figurehead, or stick with the directness of Frank Lampard and Didier Drogba. André Villas-Boas' attempts to usher in the former stalled in the face of the veterans' failure (or unwillingness) to play a high-line, pressing and passing game. The old ways have produced better results, but Chelsea doesn't quite have the physical presence in midfield anymore to make this a viable long-term strategy. It's a system that is nothing without intensity.

In the Champions League, however, the Blues have been able to revert to type. It wouldn't be the first past-its-sell-by-date team that successfully manages to channel all energy into contesting the European Cup. Adopting an outsider mentality and the matching tactics helped Roberto Di Matteo's team to circumvent it's own problems with the ball. Chelsea relied on a huge slice of luck as well as some woeful Barcelona finishing, but it's no coincidence that it has been able to consistently pose problems for the Catalan pass-masters over the years. Of all the big teams in Europe, the hardworking, tough-tackling Chelsea is best-equipped to play with the (crude) weapons of a small team. Even the grass at Stamford Bridge seemed to have been left deliberately longer than usual.

Karim Benzema could be the key man

Cristiano Ronaldo was shepherded well by a combination of Lahm, Luiz Gustavo and Robben. Angel Di Maria fared marginally better but also found it hard to break through. With Özil dropping quite deep, Madrid's most potent weapon by far was Benzema. The Frenchman turned in a superb performance full of menacing, angled runs in between the two center backs, got on the end of an amazing amount of clearances and held up the ball well for his teammates. Madrid can hurt Bayern by hitting Benzema early and shouldn't be afraid to try more direct balls if and when Bayern manage to control the wide areas again.

Toni Kroos has grown into a world-class midfielder

When the 22-year-old Kroos returned to Bayern following a two-year-spell at Leverkusen, there were doubts about his big-game mentality. He also didn't seem to have a natural position in Bayern's 4-2-3-1 system. This season, however, Kroos established himself as the most important central strategist in the light of Bastian Schweinsteiger's lengthy absence. Initially played as a no. 10 on Tuesday, Kroos dropped deep to make the extra man in the middle and was a key factor in Bayern regaining their composure after a nervy opening spell. When the still not fully-fit Schweinsteiger was substituted early in the second half, Kroos played alongside Luiz Gustavo and excelled there, too. Experts are unsure which role suits him better but everyone can agree that he's the heart and brain of Bayern while Schweinsteiger continues to seek his form. If he can dictate the game as much as he managed to in the first leg, Bayern will stand a chance to weather the storm.

Ramires is the perfect counterattacking midfielder

The Brazilian midfielder has not quite developed into "the new Michael Essien" in West London -- he has a habit of going down dead ends with the ball and lacks creativity. But in using him as defensive wide midfielder, Di Matteo utilized his skill-set perfectly. Ramires' powerful running and physical presence provided excellent cover in front of Ashley Cole. Pep Guardiola seemed to have him in mind when he suggested that Chelsea "jump more, run, run, run and has more legs than us" after the final whistle. Shortly before the break the 25-year-old Ramires outran the whole Barca defense to get to Frank Lampard's ball and set up Drogbas' lucky punch. In Barcelona, he should get more opportunities to exploit the space that Barca's midfield leave behind.