AC Milan, who beat Auxerre in their opening match, were held 1-1 by Ajax. Mounir El Hamdaoui put them ahead after 23 minutes but former Ajax hero Zlatan Ibrahimovic levelled for Milan 14 minutes later, after an assist from another one-time favourite of the home crowd, Clarence Seedorf.
Roma recovered from their opening defeat to Bayern Munich in Group E by beating CFR Cluj 2-1.
Defender Philippe Mexes fired in a crisp shot for the opener after 69 minutes and Marco Borriello struck a superb volleyed two minutes later.
Cluj replied seven minutes later when Ionut Rada headed in, but they could not find an equaliser.
Bayern came from behind to win 2-1 at Basle, who led from the 17th minute thanks to Alexander Frei’s elegant curling strike. Bayern levelled with a penalty from Bastian Schweinsteiger in the 56th minute, after Thomas Muller was impeded by Benjamin Huggel, and Schweinsteiger struck again with a minute remaining.
Aiden McGeady’s Spartak Moscow joined Chelsea at the top of Group F on six points from two games after a 3-0 home win over MSK Zilina, Ari scoring twice before Ibson added the third.
Arsenal and Shakhtar Donetsk look set to dominate Group H after both eased to the six-point mark.
In Group H Shakhtar Donetsk swept Braga aside 3-0, with Luiz Adriano scoring twice. Douglas Costa hit a stoppage-time penalty.