Barcelona's Lionel Messi has a bruised left knee and is a doubt for the leaders' next match in La Liga this weekend, the club said todayending fears that the player had suffered a more serious injury.

"Tests carried out tonight have confirmed that the player has a bruising of the bone on the outside of the left knee," Barca said in a statement.

"The rate of his recovery will determine whether he will be available for the next game, on Monday (NZ time) against Real Betis."

The World Player of the Year was carried off on a stretcher near the end of their Champions League Group G match at home to Benfica.

The Argentine collapsed to the ground clutching his knee after colliding with Benfica goalkeeper Artur and looked to be in severe discomfort as he was taken from the pitch.

The initial diagnosis was that he had suffered only bruising.

"After beating the offside trap Messi tried to dribble round opposing keeper Artur, who dealt him a blow, but Messi continued with the move," Barca said in a statement on their website (www.fcbarcelona.com).

"After shooting with his left foot the player fell to the ground with pain in his left knee," the statement added.

The game ended 0-0 with Barca already through to the last 16 as group winners and Benfica forced to settle for a place in the Europa League.

Messi remains one goal short of Gerd Mueller's record of 85 goals in a calendar year set in 1972.

The last time Messi suffered an injury was in September 2010 at Atletico Madrid when a hefty challenge left him with ankle damage that ruled him out of two games, the club said.

Benfica missed out on a place in the last 16 with the 0-0 draw with a weakened Barcelona to finish third behind Celtic in Group G.

Celtic won 2-1 at home to Spartak Moscow to finish with 10 points, three behind already qualified Barca. Benfica had eight.

The visitors carved a number of openings in the first half but were profligate with their shooting. They ran out of ideas and steam, although they almost grabbed a dramatic goal in time added on.

Barca coach Tito Vilanova rested regulars such as Victor Valdes, Xavi, Andres Iniesta and Cesc Fabregas in favour of a number of youth team players, and surprisingly left Messi on the bench.

Benfica forward Rodrigo fired wide of the post in a three-on-one chance with Jose Manuel Pinto after 12 minutes, as Barca lacked their usual fluidity and were pressed back.

The chances came and went for Benfica and the home crowd's chants for Messi to come on were satisfied in the 58th minute, but he appeared to damage his knee and left the pitch in pain with five minutes to go.

Benfica's Maxi Pereira blazed a shot over the bar in the fifth minute of time added on and with it went their chances of qualifying for the next round.

- Reuters