Barcelona's Brazilian star player Ronaldinho at a practice session earlier this month. - reuters

LONDON (AP):

FC Barcelona begin the the defence of their European Champions League title today in a confident mood. If only runners-up Arsenal could say the same.

Barcelona have won both of their Spanish league games so far, scored six goals and have no injury concerns ahead of their match against Bulgaria's Levski Sofia at the Camp Nou.

It's one of eight matches on the opening day of the group stage of the competition. In other matches, Barcelona's Group A rival Chelsea hosts Werder Bremen, Inter Milan are at Sporting Lisbon and 2005 champions Liverpool travel to PSV Eindhoven.

Also, it's Galatasaray vs. Bordeaux, Olympiakos vs. Valencia, AS Roma vs. Shakhtar Donetsk and Bayern Munich vs. Spartak Moscow.

Arsenal play tomorrow travelling to Hamburg. The Gunners have had their worst start ever in the English Premier League, drawing two and losing one.

"It is not a lack of concentration, maybe we are just not quite there yet," Arsenal striker Thierry Henry said. "We cannot be disappointed with the way we are playing even though we are not putting the ball in the net, which is the most important thing."

Special match

Also tomorrow Manchester United host Celtic, which will be a special match for respective managers Alex Ferguson and Gordon Strachan.

Ferguson coached Strachan at Scottish club Aberdeen - when they won the European Cup Winners' Cup in 1983 - and later at Manchester United.

Barcelona coach Frank Rijkaard has no injury concerns entering today's match, which will see the club break with tradition with it sporting an advertisement on the front of its shirts for the first time in a competitive match. Barcelona will promote the United Nations' children's charity UNICEF.

"We must respect Levski as a good team with international players. In the Champions League it is always necessary to prepare properly and we will do so for the game," Rijkaard said.

Chelsea are expected to play Claude Makelele after he was rested for the 2-1 English Premier League win over Charlton on Saturday, while new left back Ashley Cole also could make his first start for the Blues.

Chelsea have some inside information on Werder Bremen from midfielder Michael Ballack, who moved to England this season from Bremen's fellow German club Bayern Munich.

"They are a team that thinks very offensively," Ballack said. "They want to score every game. But sometimes they give chances to the other team and make mistakes in defence."

Bremen were eliminated from the German Cup by third-division Pirmasens on penalty kicks Saturday, but played without Germany internationals Torsten Frings, Tim Borowski - who were rested with minor injuries - along with Per Mertesacker, who is doubtful with a heel injury.

Liverpool travel to PSV Eindhoven after losing the 204th Merseyside derby 3-0 to Everton -_ the worst league loss to their crosstown rival since 1964.

John Arne Riise re-injured his left ankle and will miss the PSV match, where the English club's defence will be under scrutiny.

"We made a lot of mistakes, too many mistakes and our defending was really poor," Liverpool manager Rafa Benitez said.

Former Liverpool defender Jan Kromkamp likely will start at right back for PSV, which is also expected to debut new acquisition Patrick Kluivert.

PSV coach Ronald Koeman was coach of Benfica last season, when the Portuguese club eliminated Liverpool from the second round.

Inter Milan opened the Italian season with a 3-2 win at Fiorentina but coach Roberto Mancini said the players needed "more determination and attention in defence."

Mancini said Esteban Cambiasso, defender Marco Materazzi and Patrick Vieira could be rested against Sporting Lisbon.