Barcelona striker Leo Messi scored an incredible four times as his side beat Arsenal 4-1 to qualify for the semifinals of the Champions League on Tuesday night.

The Argentinean showed why he is the best player in the world with a first half hat-trick after the visitors had taken a surprise first half lead.

Both sides went into the game with numerous players missing: Barcelona was without suspended duo of Carles Puyol and Gerard Pique, while Zlatan Ibrahimovich was missing with a calf strain, allowing Bojan to start in attack.

The young striker had scored two goals at the weekend and got the nod ahead of former Arsenal hero Thierry Henry.

The visitors meanwhile had a host of injuries, including Cesc Fabrigas, William Gallas, Alex Song, Andrey Arshavin and young midfielder Alex Ramsey, limiting the options of coach Arsene Wenger, who opted to use Mikael Silvestre in central defense while leaving veteran Sol Campbell on the substitutes' bench.

The 2-2 draw from the first leg meant that Arsenal had to score to have any chance of qualifying for the last four and although Barcelona began by controlling the play Arsenal did indeed score the first goal.

Abu Diaby robbed possession in midfield, fed Theo Walcott and the winger's pace allowed him to cross the ball for Nicklas Bendtnaar to score at the second attempt after 19 minutes.

That goal threatened to upset Barcelona, but Messi got them back on level terms just two minutes later. The ball fell kindly to him on the edge of the Arsenal area and he produced an unstoppable left foot shot.

Barca continued to dominate and took the lead after 37 minutes. Eric Abidal cut in from the left and his ball into the area was knocked down by Pedro for Messi to control and beat Manuel Almunia from close range.

There was still time in the half for Messi to complete his hat-trick. As the Arsenal defense pushed forward, he ran onto a smart header from Keita before clipping the ball over a stranded Almunia.

With the tie under control, Barcelona looked to control the game in the second half and reserve energy for next Saturday's visit to play Real Madrid.

Toure Yaya came into the game to close down space and with Arsenal unable to create chances and Barcelona content to let the clock tick down it made for a dull spectacle.

Three minutes from time, however, Messi made it all worthwhile. Again he found space in the Arsenal half and although Almunia stopped his first shot, Messi slotted the rebound through the keeper's legs.

Barcelona won 4-1 on the night, 6-3 on aggregate and Messi now has 25 goals in 41 Champions League appearances, making him the club's record scorer in the competition along with Rivaldo.