London: Barcelona conceded one of the fastest goals ever scored in the Champions League and then suffered the shock of a stoppage-time equaliser as they began the defence of their crown with a 2-2 draw at home to AC Milan.
Chelsea`s annual pursuit of the continent`s biggest club prize that has so far eluded them began in encouraging fashion for the latest coach in the hot seat as Andre Villas-Boas`s team beat Bayer Leverkusen 2-0 in Group E.
The other Anglo-German tussle among the eight matches in Groups E-H ended in a 1-1 draw between Bundesliga champions Borussia Dortmund and Arsenal in northern Germany.
While Chelsea and Arsenal still seek a first Champions League crown, former European champions Porto and Olympique Marseille began with victories.
Porto beat Shakhtar Donetsk 2-1 in Group G although they were helped by their Ukrainian opponents having two players sent off -- Yaroslav Rakitskiy for a straight red card in the 40th minute for a poor tackle and Dmytro Chygrynskiy for a second booking late on.
In Group F, French side Marseille edged out Olympiakos Piraeus 1-0 in Greece.
Newcomers Viktoria Plzen got their first point on the board with a 1-1 draw at home to BATE Borisov of Belarus although with Barcelona and Milan waiting in Group H life is about to get much tougher for the Czechs.
The standout fixture of the night in the Nou Camp exploded into life when Milan`s Alexandre Pato surged through a flat-footed Barca backline to score the fifth-fastest goal in the competition, timed at 24 seconds.
It took Barcelona a while to clear their heads but the Catalans went level before halftime when Lionel Messi, top scorer in the competition for the past three years, turned provider with a perfect cut back for Pedro to tap in.
David Villa`s sublime curling free kick after 50 minutes put Barca in front and, with their striker Zlatan Ibrahimovic missing through injury, Milan rarely threatened to get back on level terms.
However, the Serie A champions struck again at the death when Thiago Silva rose above the home defence to head home from a corner in the second minute of stoppage time.
A frustrating night for Barca was summed up by a leg muscle injury sustained by midfielder Andres Iniesta that will keep him out for four weeks. Iniesta was replaced before halftime by new signing Cesc Fabregas.
"It wasn`t easy trying to penetrate the opponent`s penalty area crowded with eight defenders," Barca coach Pep Guardiola told reporters. "We tried but at the end they levelled from a corner."
Milan coach Massimiliano Allegri, whose side were under pressure for long periods, was satisfied with a point.
"Barca are still the best team in the world but sometimes even they can draw," he said.
Chelsea welcomed back Michael Ballack to Stamford Bridge but it was not to be a happy return for the German midfielder as goals by Brazil defender David Luiz and Spain forward Juan Mata gave Villas-Boas the perfect start to the campaign.
Both goals were set up by Spain striker Fernando Torres, recalled to the side after being left out of Chelsea`s Premier League victory at the weekend because of poor form.
"He took the right decision," Villas-Boas told the club`s website (www.chelseafc.com) when describing Torres`s unselfish decision to pass to Mata rather than try to double his meagre tally of one goal since arriving for a British record fee of 50 million pounds from Liverpool in January.
"We had players there with the goal in front and he took a wise decision so we`re very happy for that."
Arsenal looked on course for a notable win at Borussia Dortmund thanks to Robin van Persie`s clinical finish just before halftime but a stunning 88th-minute volley by Ivan Perisic denied the Gunners whose manager Arsene Wenger had to watch the match from the stands because of a touchline ban.
Cypriots Apoel Nicosia were up against Russian opposition for the first time and marked the occasion with a 2-1 defeat of visitors Zenit St Petersburg -- a result greeted with euphoria by the 18,000 home fans who celebrated their team`s first victory in the group stages of the Champions League.
Two goals in three minutes by Gustavo Manduca and Ailton turned the match around after Konstantin Zyryanov fired Zenit ahead against the run of play in the 63rd minute.
Zenit`s Bruno Alves was sent off in the 76th minute.
Belgium side Genk are still waiting for their first victory in the group stage of the competition, after they made their only other appearance nine years ago, but were satisfied with a 0-0 home draw against Valencia in Group E.
Wednesday`s action includes Benfica hosting last year`s runners-up Manchester United in a repeat of the 1968 European Cup final while ambitious Manchester City make their debut at home to Napoli.