Alessandro Del Piero, 33, scored with a longe-range swerving free-kick to give Juventus a 1-0 home win over Zenit St Petersburg on their return to the Champions League group stages yesterday.
In the other Group H match, newcomers BATE Borisov got away lightly with a 2-0 defeat against Real Madrid at the Bernabeu and a goal from Karim Benzema four minutes from time enabled Lyon to salvage a 2-2 draw with Fiorentina in Group F.
Manchester United began their Champions League title defence with a 0-0 draw at home to Spain's Villarreal.
The return of Portuguese winger Cristiano Ronaldo, who came on as a 62nd-minute substitute after recovering from ankle surgery, failed to spark the home side.
Ronaldo was given a standing ovation by the United fans, who appear to have forgiven the winger for wanting a move to Real Madrid in the close-season.
Defender Jonny Evans went closest when he headed against a post from a Ronaldo cross but Villarreal also hit the woodwork as they held out to deny United a 13th successive home win in the competition.
Del Piero, who played in the final when the Turin club won the second of their two European Cups in 1996, netted on 76 minutes in their opener with Zenit goalkeeper Vyacheslav Malafeyev looking at fault.
Juve, back in the group stages after missing out the last two seasons following their domestic demotion for match-fixing, made hard work of the win against the Champions League debutants.
UEFA Cup holders and Russian champions Zenit had the first clear chance when striker Danny scuffed wide from close range.
Juve had other chances of their own however, with David Trezeguet heading just past the post from strike partner Del Piero's clipped cross.
Winger Mauro Camoranesi, who later left the field injured, headed another good Del Piero cross against the outside of the post while midfielder Christian Poulsen went close with a flick in the second half.
Striker Alberto Gilardino put Fiorentina in front against the run of play on 12 minutes, heading home a Luciano Zauri cross, and doubled their advantage shortly before the break with another header, this time from a cross by Felipe Melo.
Seven-times French champions Lyon, who have never advanced past the quarter-finals of European club soccer's premier event, scored on 73 minutes when substitute striker Frederic Piquionne tapped in from a Benzema pass.
France striker Benzema then saved Lyon from defeat with an angled effort from inside the box after a Juninho free-kick.
Sergio Ramos gave nine-times European champions Real Madrid an early lead and they threatened an avalanche of goals but Borisov held firm until early in the second half.
Ruud van Nistelrooy doubled the advantage with his 54th goal in the competition and any thoughts of a fightback by the team from Belarus effectively disappeared when defender Anri Khagush was sent off soon after.
Celtic struggle
Celtic's Barry Robson missed a first-half penalty in a goalless draw with 10-man AaB Aalborg as the Danes dominated most of the first half but failed to take their chances against the Scottish champions.
Celtic's Shaun Maloney was felled by a late, sliding tackle from Dutch defender Steve Olfers with 29 minutes gone, only for Robson to strike the ball against the legs of Moroccan goalkeeper Karim Zaza.
Aalborg had Michael Beauchamp sent off with 10 minutes to go after Italian referee Matteo Trefoloni wrongly ruled the Australian defender had tripped Georgios Samaras in a scoring position, instead of team-mate Michael Jakobsen.
In Group G, France defender William Gallas scored two minutes from time to salvage a 1-1 draw for Arsenal against Dynamo Kiev.
Gallas converted from close range at the far post after Theo Walcott's low cross into the danger area had taken two deflections.
Kiev, who lost all six group games in the competition last season, had looked set for victory after Guinea striker Ismael Bangoura scored a 64th-minute penalty.
Bangoura easily beat keeper Manuel Almunia after Bacary Sagna had tussled with Ognjen Vukojevic.
In the other Group G match, two goals in two minutes from Argentines Lisandro Lopez and Lucho Gonzalez helped Porto to a 3-1 win over Fenerbahce.
Spanish striker Daniel Guiza reduced the deficit for Fenerbahce when he tapped in a rebound after Porto's Helton failed to clear a header by Brazilian Alex after 29 minutes.
Substitute Lino made the three points safe for Porto with the third goal in the stoppage time.
An early goal from Daniel Van Buyten helped Bayern Munich to a 1-0 win at Steaua Bucharest to go top of Group F ahead of Lyon and Fiorentina.
Van Buyten headed home the winner in the 15th minute following a free-kick from Bastian Schweinsteiger.
Steaua's Colombian playmaker Dayro Moreno angled in a powerful 30-metre shot during the first half but visiting keeper Michael Rensing deflected the ball with his right-foot.
In the second half, Steaua's Brazilian striker Arthur Bernhardt also hit the post.