UEFA Champions League: 5 Things We Learned From Matchday 1

The group stages of the 2011-12 UEFA Champions League got underway this week, with all 32 remaining teams in action across Europe.

On Tuesday night the big stories were Barcelona's 2-2 draw with Milan and Borussia Dortmund's late goal to salvage a point at home to Arsenal.

Wednesday saw attentions turn to the Premier League's two Manchester clubs. United drew away at Benfica, while City were held at home by Italian side Napoli. There was also a monumental shock at the San Siro, with Inter Milan beaten by Trabzonspor of Turkey.

Here are five things we learned from Matchday 1.

1. Borussia Dortmund Can Challenge This Season

German champions Borussia Dortmund had to rely on a late goal from substitute Ivan Perisic against Arsenal to avoid an opening day defeat, but judging on their overall performance have a real chance of going deep in the competition this year.

In Mario Gotze and Shinji Kagawa they boast two of the Champions League's most exciting attacking players and appear a team overflowing with confidence right now.

Assuming the make it through the group stages, which they should, the likes of Barcelona and Manchester United will be keen to avoid them in the knock-out rounds.

2. Barcelona Are Vulnerable

Nobody should expect Barcelona to win every match they play, but the two goals they conceded against AC Milan will not have pleased Pep Guardiola from a defensive standpoint.

Alexandre Pato danced through the heart of Barca's defense inside a minute to put Milan ahead, while Thiago Silva's late equalizer from a corner was as straightforward as they come.

Barca desperately need Gerard Pique back from injury, and Guardiola would be wise to bring in some stronger cover during the January window.

3. Milan Are Not to Be Underestimated

AC Milan have the oldest squad in the Champions League this season, but that's not necessarily a bad thing.

With experienced heads like Clarence Seedorf, Alessandro Nesta, Gianluca Zambrotta and Mark van Bommel on duty, they'll be ready for every eventuality and very hard to beat.

Don't be surprised if they make it to the semifinals or beyond.

4. Anders Lindegaard Could Be the Man for Manchester United

Sir Alex Ferguson turned to his reserve goalkeeper Anders Lindegaard last night, and the Dane delivered a compelling argument that he can challenge David De Gea for a starting spot this season.

Lindegaard didn't put a foot wrong against Benfica, and said afterwards he was fully committed to the challenge of becoming United's No. 1. "As I've said 1,000 times before, I'm not here to pick my nose."

5. Manchester City Have Much to Learn

Manchester City have hit the ground running in the Premier League this season, but Napoli gave them a lesson in progress at the Etihad Stadium last night.

Reports suggest the Italians were the better side overall and City manager Roberto Mancini may have to re-think how he approaches home ties in future.

In a group that also contains Bayern Munich and Villarreal time is clearly of the essence.