Leo Messi scored twice as FC Barcelona beat Danish side Copenhagen 2-0 in the Champions League on Wednesday.

The win leaves Barcelona top of their qualifying group, but coach Pep Guardiola won't be happy with the way his side missed chances to seal the win in the first half and then had to suffer before Messi wrapped up the result in the final minute.

Barcelona suffered a blow in the hours before kick off when goalkeeper Victor Valdes was forced out of the squad suffering from a virus. He was replaced in the side by reserve keeper Pinto.

Meanwhile Guardiola made several other chances to his side, resting midfielder Xavi Hernandez and striker Pedro Rodriguez, while bringing Javier Mascherano into the side and pushing Maxwell forward to play on the left of midfield.

Barcelona began pushing the Danes deep into their own half and as early as the fourth minute David Villa came within inches of opening the score when he got past his man only to fire against the crossbar.

Copenhagen goalkeeper Willard had to be at his best after 10 minutes when Maxwell threatened to finish Dani Alves' far post cross.

He was in action again after 17 minutes to deny a Messi header, but was helpless three minutes later. Messi received a pass from Andres Iniesta on the edge of the penalty area before looking up and picking his spot to make it 1-0.

Barca kept pressing and it was Willard who was the hero again 10 minutes before time with another save to deny David Villa.

That nearly turned out to be vital as Copenhagen showed more life after the break and N'Doye hit the crossbar midway through the second period.

Bolaos also wasted a great chance after 74 minutes and Guardiola decided to throw Xavi into the game.

The entry of the Spain international returned the control of the ball to his side, Alves his the post a minute from time before Messi netted his second of the night.

Abidal's shot was going nowhere but the Argentinean was onto it quickly to net his second of the night and assure a vital win for his side.