Lionel Messi, grimacing in pain, was taken off the field on a cart with bone bruise to his left knee as Barcelona was held to a 0-0 tie by Benfica in a Champions League match on Wednesday night.
With Barcelona already assured of advancing to the second round, Messi entered as a reserve in the 58th minute.
Messi's left knee collided with the right hand of Benfica's Artur as he ran onto Gerard Pique's long pass and tried to round the goalkeeper in the 85th minute. Messi took a left-footed shot from an angle, then fell to the field in pain. He rolled onto his back and held the knee, then was loaded onto a cart.
''It's a bruise, which doctors have been having a look at,'' Barcelona coach Tito Vilanova said. ''We now have to wait for the results of tests, but the feeling is that it isn't more serious than a knock.''
Barcelona later tweeted that tests confirmed Messi has a bruised bone on the outside of his left knee.
A three-time FIFA Player of the Year, Messi has 84 goals for Barcelona and Argentina this year, one shy of Gerd Mueller's 40-year-old record for most goals in a calendar year for club and country.
''Had we been worried just about the record we would have played Messi right from the beginning,'' Vilanova said. ''But we had talked about it and decided to bring him on with half an hour to play.''
