Barcelona's quest to become the first team in history to retain the UEFA Champions League got off to a rocky start with a draw to AC Milan as the home side conceded both in the first minute and deep into second-half stoppage time. 

Alexander Pato put visiting AC Milan ahead after just 25 seconds with an expertly taken goal. The Brazilian international streaked through a Barcelona defense that was caught flat-footed to slot the ball past Victor Valdes. A goal nine minutes before halftime from Pedro drew the Spanish giants level. Lionel Messi's slashing run led to a simple cross and a point-blank tap-in from Pedro. David Villa seemed to give Barcelona the victory with a curling free kick from just outside the area in the 50th minute. However, AC Milan had one more push forward and deep into injury time, Thiago Silva's header gave the Italians a vital away draw. 

Arsenal will be disappointed with conceding a late goal but a 1-1 draw against Borussia Dortmund is as good a result as Arsene Wenger's men could have hoped for.

A brilliant volley from substitute Ivan Perisic salvaged a point for the German champions in the 88th minute. Per Mertesacker headed clear a Dortmund corner kick but the ball found it's way to the Croatian international, who came up with a gem of a goal. Robin Van Persie had put Arsenal up with a clinical finish off an incisive through ball from Theo Walcott in the first half.

Chelsea were less than convincing in the early stages against visiting Bayern Leverkusen but the Blues had enough firepower to start of their Champions League campaign with a win.

Michael Ballack made his return to Stamford Bridge while $79 million striker Fernando Torres failed to score once again. David Luiz marked his season debut with a goal in the 67th minute with an assist from the struggling Torres. Juan Mata continues to impress during his short stint with Chelsea and gave the home side an insurance policy with a goal in injury time. Torres unselfishly provided the assist when he could have opted to go for goal.

In other results, FC Porto was able to overcome an early deficit to claim victory over Shakhtar Donetsk in their Group G opener. Hulk and Kleber canceled out Luiz Adriano's goal in the 12th minute. 

Valencia recorded 22 shots but couldn't find the back of the net as KRC Genk held out for a surprising draw. Hungarian goalkeeper Laszlo Kotele made four saves in the shutout. In Greece, Marsielle find themselves top of Group F with a win in Athens against Olympiakos. Lucho Gonzalez scored just after the restart to give the French side the win.

Cyrpus side Apoel Nicosia temporarily finds itself joint-top of Group G after a 2-1 victory over Russian club Zenit St. Petersburg. Gustavo Manduca and Ailton Almeida scored within two minutes of each other to give Apoel Nicosia the comeback victory. Viktoria Plzen and Bate Borisov could have taken advantage of Barcelona and Milan's draw to go top of Group H but the Eastern Europeans ended deadlocked at one.

Tuesday's scoreboard

Group E

Chelsea 2, Bayern Leverkusen 0

Valencia 0, KRC Genk 0

Group F

Marseille 1, Olympiakos 0

Arsenal 1, Borussia Dortmund 1

Group G

Apoel Nicosia 2, Zenit St. Petersburg 1

FC Porto 2, Shakhtar Donetsk 1

Group H

Barcelona 2, AC Milan 2

Viktoria Plzen 1, Bate Borisov 1

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What did you think of today's results? Does Barcelona's defense worry you? Grateful for Arsenal's point? Can Chelsea make a deep run in the Champions League?

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