Shakhtar Donetsk led the way for the Champions League underdogs as they beat holders Chelsea 2-1 while former European champions Barcelona and Manchester United came from behind to maintain perfect starts on Tuesday.
Danish debutants FC Nordsjaelland were within nine minutes of a memorable win over Juventus before having to settle for a 1-1 draw while last season's beaten finalists Bayern Munich bounced back from a shock defeat by BATE Borisov on Matchday Two to beat Lille 1-0 in France.
A year to the day since Chelsea captain John Terry racially insulted Anton Ferdinand of Queens Park Rangers, for which he is now serving a four-match domestic ban, he is eligible to play in Europe but could not stop Shakhtar scoring after three minutes.
He failed to clear a pass to Alex Teixeira who took advantage of poor defending to angle a shot past Chelsea's Petr Cech who then made several fine saves to keep the score down.
Fernandinho doubled the home side's lead after halftime before Oscar became the third Brazilian to score in the match with a late consolation for the well-beaten visitors.
"We are not afraid of playing against teams like Chelsea," said Shakhtar's Romanian coach Mircea Lucescu. "I think we deserved this victory - we created many more opportunities and the score could have been 4-1.
"Cech had an extraordinary game tonight. Maybe Chelsea started a bit too relaxed."
Roberto Di Matteo, whose Chelsea side lost their first Champions League game since he became manager in March, said: "Shakhtar have a good track record at home, particularly against the English teams.
"It's very difficult when you concede a fast goal. It's a shame we got back into the game a bit late. I believed we could score a goal at least but they punished us after we lost the ball in midfield. We have to do better as a team in those situations."
The result left the Ukrainian side at the top of Group E with seven points, three more than Chelsea. Juventus have three and Nordsjaelland one.
Juve have now drawn their last nine European matches, and salvaged a point when Mirko Vucinic equalised nine minutes from time. Nordsjaelland, ahead through a 50th minute Mikkel Beckmann goal, at least hung on for their first point in the competition.
"That was a fantastic achievement but I think we can get even better," Nordsjaelland coach Kasper Hjulmand told TV 3Plus.
Unlike Chelsea, who failed to come back after falling behind, Barcelona, European champions three times in the last seven seasons, did just that.
But they needed a goal in the fourth minute of stoppage time from Jordi Alba to beat Celtic 2-1 after the 1967 European champions had taken the lead at the Nou Camp through Javier Mascherano's own goal after 18 minutes before Andres Iniesta's brilliantly-worked equaliser just before halftime.
Alba told Spanish TV he was lucky to be in the right place at the right time.
"It was a move involving the whole team and I just had the good fortune to be in the right place," he said. "I don't know what the Celtic players eat, but they are very powerful in the air, in defence as well as attack," he added.
Barca lead Group G with nine points from three wins, ahead of Celtic on four while Spartak Moscow have moved on to three points after their first win of the campaign, 2-1 at home to Benfica thanks to Jardel's own goal.
Manchester United avoided an upset at Old Trafford, coming from behind to beat Braga 3-2 after being 2-0 down inside the first 20 minutes as Alan found the key to unlocking United's defence with two crisp finishes.
United fought back with two headers from Javier Hernandez either side of a Jonny Evans goal which he scrambled in with his left foot after missing his kick with his right one.
United manager Alex Ferguson told ITV that conceding early goals was a fault they needed to correct.
"It has been the story of our season at home, starting badly and losing goals," he said. "We have had to rescue games and it is the front players doing that. We played some terrific football tonight, but it is a concern losing the goals."
It was United's third successive win and they top Group H with nine points, followed by CFR Cluj on four after they drew 1-1 at Galatasaray. Braga have three and the Turkish side one.
In a lively match in Istanbul, Cluj had Matias Aguirregaray sent off after 28 minutes and Felipe Melo missed a penalty for Galatasaray seven minutes later.
Dany Nounkeu put through his own net to give Cluj the lead after 19 minutes before Burak Yilmaz equalised for the home side 13 minutes from time.
Valencia ended BATE Borisov's perfect start in Group F with Roberto Soldado's hat-trick securing a 3-0 win in Belarus. With Bayern winning 1-0 at Lille with a Thomas Mueller penalty, Valencia, BATE and Bayern all have six points with Lille on none.