A Lionel Messi strike saw Barcelona maintain their two-point lead at the top of Group H after drawing 1-1 at AC Milan in the Champions League.
The Argentine struck in the 23rd minute with a fine finish to a breakaway move to cancel out Robinho's stylish ninth minute opener, which came during a frantic opening period of pressure from the home side.
Barcelona moved up to seven points, with unbeaten Milan in second spot on five, two ahead of Celtic who beat Ajax 2-1 in Glasgow.
Barca dominated the second half against a tired Milan, but despite a couple of good chances couldn't make the most of their possession and had to settle for a point.
Alexander Kerzhakov scored the winner with just four minutes remaining as Zenit St Petersburg overcame 10-man Porto 1-0 in UEFA Champions League Group G.
Hector Herrera was sent off after just six minutes but the home side refused to back down and had the better of a cagey first half.
But in the 86th minute the impressive Hulk crossed for Kerzhakov to score and fire Zenit into second place in the group behind Atletico Madrid.
Diego Costa scored twice as Atletico Madrid maintained their perfect record in Champions League Group G with victory over Austria Vienna.
Costa, the Brazil-born striker who is being courted by Spain, netted in each half of the 3-0 success, which was kick-started by Raul Garcia's 20th-minute opener.
While Diego Simeone's side now have a maximum of nine points, the hosts are struggling with just one from their first three games.
An 88th-minute goal by substitute Leandro Tatu salvaged a 1-1 home draw for bottom club Steaua Bucharest in their Champions League Group E match against Basel at the National Arena on Tuesday.
Basel took the lead three minutes after the interval when Chilean midfielder Marcelo Diaz gave keeper Ciprian Tatarusanu no chance with a delightful curling shot from outside the area after a blunder by Iasmin Latovlevici.
The Swiss club, who beat Chelsea in their opening game, are now third in the group with four points, two behind the Londoners and Schalke 04.
Steaua, winners of the European Cup in 1986, have one point.
Elsewhere, Napoli continued their impressive European campaign with a 2-1 victory away at Marseille.
Jose Callejon put Napoli ahead three minutes before the break and Duvan Zapata put Rafael Benitez's men clear as they bounced back from their weekend loss to Roma.
Andre Ayew struck for the hosts with four minutes left but it was too late, with Arsenal, Napoli and Dortmund all tied together on six points.