The World Player of the Year single-handedly led the European champions into a semi-final meeting with Inter Milan, the Argentine scoring all Barca's goals in a 4-1 victory at the Nou Camp on Tuesday.
NEWS:Messi 4-1 Arsenal
"Messi can make a difference at any moment in a game. He can take advantage of any mistakes you make," Wenger told a news conference.
"Messi's very young but he can achieve a lot. I don't know many players who can score the four goals he scored tonight and he has the team to help him.
"Barca is more than Messi. They are an exceptional team with an exceptional player. In exceptional games it is the exceptional players that make the difference."
The 22-year-old Messi grabbed his team by the scruff of the neck and dragged them back into the game after they were shaken by Nicklas Bendtner's 18th-minute opener.
He arrowed towards the area three minutes later and when Mikael Silvestre's weak clearance rebounded back into his path, he hammered a shot high into the net for the equaliser.
He pulled wide and fired the second over the diving Arsenal goalkeeper in the 37th minute and then completed his hat-trick with a scooped lob over the advancing Manuel Almunia, after bursting away on a counter-attack just before the break.
The fourth, at the end, saw Messi nut-meg Almunia after twisting and turning past defenders inside the area.
"He is a brilliant player. He was fantastic," Almunia, told Sky Sports.
"As a goalkeeper you try and anticipate what he is going to do but he can do anything so it is very hard to stop him because he has such fantastic skill.
"He was great tonight, I think he is the best player I have ever played against and is the best in the world."
IMPOSSIBLE TO IMITATE
Barca coach Pep Guardiola was fulsome in his praise for the work ethic of Tuesday night's matchwinner.
"There is no way to describe Messi's performance. There are no words. You have to see it," he told reporters.
"He deserves everything he achieves because of his love for the game. He's a great example for the young players. But he's impossible to imitate."
But Guardiola was quick to stress the 'behind the scenes' work of his squad as a whole, when seeking to explain Messi's brilliance.
"There are many players who know they will not be in the headlines but play out of position sometimes for the good of the team.
"If we don't play well...Messi might not do so well. We don't ask him to score four goals. We ask him to enjoy himself on the ball when he gets it. Sometimes it works other times it doesn't.
"We just want him to have fun."
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