ROME (AP) -- Lionel Messi scored a hat trick as Barcelona opened Champions League play with a 4-0 win over Ajax on Wednesday.
It was a different story for Jose Mourinho, though. Chelsea got off to a losing start for the first time, with Basel coming from behind to win 2-1 in London and add to the difficulties of the ''Special One'' during his Stamford Bridge homecoming.
Last season's runner-up, Borussia Dortmund, also had a bad night, losing 2-1 at Napoli with both coach Juergen Klopp and goalkeeper Roman Weidenfeller ejected.
Seven-time champion AC Milan struggled, too, before two late goals gave the injury-riddled Rossoneri a 2-0 victory at home over Celtic.
Meanwhile, Theo Walcott and Aaron Ramsey scored as Arsenal won 2-1 at Marseille.