Diego's 84th-minute equaliser gave Werder Bremen a 1-1 draw at home to Milan, while Valencia were also held to a draw by Dynamo Kiev in the first leg of the Uefa Cup Round of 32.
Poacher supreme Pippo Inzaghi gave the Rossoneri a 36th-minute lead at Bremen only for the Italians to be pegged back late on by Diego.
David Silva gave Valencia an early lead in Kiev, but a second-half own goal from Raul Albiol saw the match end in a draw. The hosts ended the game with only 10 men after Artem Milevsky's dismissal for a second bookable offence.
Elsewhere, goals from Szabolcs Huszti and Anatoli Tymoschuk gave Zenit St Petersburg a 2-1 win against Stuttgart. Mario Gomez equalised in the first half for the visitors.
Martin Jol's Hamburg triumphed 3-0 at Hamburg, with the Germans' goals coming from Piotr Trochowski, Alex Silva and Ivica Olic.
Full results:
Dynamo Kiev 1 - 1 Valencia
Zenit St Petersburg 2 - 1 Stuttgart
Olympiacos 1 - 3 St Etienne
Aston Villa 1 - 1 CSKA Moscow
Werder Bremen 1 - 1 Milan
Bordeaux 0 - 0 Galatasaray
NEC Nijmegen 0 - 3 Hamburg
Paris Saint Germain 2 - 0 Wolfsburg
Sampdoria 0 - 1 Metalist Kharkiv
Aalborg 3 - 0 Deportivo La Coruna
Braga 3 - 0 Standard Liege