Romania's CFR Cluj shocked AS Roma 2-1 on their Champions League debut on Tuesday but there were no surprises for big guns Chelsea, Liverpool, Barcelona or Inter Milan who all won their opening group games.
Christian Panucci had put Roma ahead in the 16th minute at the Stadio Olimpico, but two goals from Juan Culio after 28 and 49 minutes handed the Romanians victory in Group A.
"Starting this way at this level is incredible," Cluj's Italian coach, Maurizio Trombetta told reporters. "We did all we could to shut down Roma's play."
Disappointed Roma midfielder Daniele De Rossi said: "At the moment things are not working. Some of it is bad luck, but we're making things complicated all by ourselves. But we'll get through it, we've done great things in the past."
Last season's runners-up Chelsea opened their account in the same group with a 4-0 demolition of Girondins Bordeaux to give coach Luiz Felipe Scolari his first win in the competition.
However, goals from Frank Lampard, Joe Cole, Florent Malouda and Nicolas Anelka failed to satisfy the Brazilian.
"We started very well, we got three points but we made too many mistakes. We did not control the game enough, we let them have too much of the ball, especially in the second half, but we did get two late goals," Scolari told reporters.
Liverpool coach Rafa Benitez was also disappointed despite his side coming from behind to beat Marseille 2-1 in Group D. A double from captain Steven Gerrard secured the points for the 2005 winners after Lorik Cana had put the French club ahead
"The team played well and he (Gerrard) played well but the team can play better and so can he. This is positive because there is room for improvement," Benitez said.
Atletico Madrid kicked off their campaign in the same group with a comfortable 3-0 win at PSV Eindhoven. Madrid easily overcame the Dutch champions with two goals in the first half from Sergio Aguero and a second half effort from Maniche.
Werder Bremen were surprisingly held to a goalless draw by Cypriot debutants Anorthosis Famagusta in Group B -- the first team from the divided island to reach this stage of European soccer's top competition.
But there were no such problems for Inter Milan in the other Group B game. Goals from Mancini and his replacement Adriano saw the Italians beat Panathinaikos 2-0 to give Jose Mourinho his first Champions League win as coach of the Serie A holders.
After losing their last three games, Barcelona got back to winning ways with a 3-1 home victory over Sporting in Group C.
Rafael Marquez put Pep Guardiola's side ahead in the first half before Samuel Eto'o slotted home a penalty on the hour. The Portuguese hit back through Tonel in the 72nd minute, but Xavi sealed the points for the Spaniards just before the end.
Ukraine's Shakhtar Donetsk saw off the challenge of Basel with a 2-1 away win in the other match in the group.
The pick of Wednesday's matches sees champions Manchester United open their title defence at home to Villarreal in Group E with winger Cristian Ronaldo expected to return from injury. Celtic host Danish side AaB Aalborg in the same group.
Nine-time winners Real Madrid will be determined to avoid an upset at home to Belarussian debutants BATE Borisov in their opener, while Bayern Munich return after a year's absence with a trip to Steaua Bucharest and Arsenal travel to Dynamo Kiev.