Messi, 22, scored all four as the Gunners lost 4-1 on the night and 6-3 on aggregate as the European champions marched on to a semi-final against Jose Mourinho's Inter Milan.
'Messi is the best player in the world by a large distance,' said Wenger. 'It is difficult because he's not always in the game, but when he gets on the ball he's really dangerous and unstoppable.
Centre of attention: Lionel Messi hit four incredible goals to destroy Arsenal
'When he changes direction at such pace no-one can stay with him. He is very young but he can achieve a lot. He has six or seven years in front of him touch wood that nothing happens to him and he can reach unbelievable levels.
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