After scoring a hat-trick against Valencia in La Liga on Sunday, Messi netted twice and helped create another to inspire Barca to a 4-0 win over VfB Stuttgart at the Nou Camp and send the holders through to the quarter-finals 5-1 on aggregate.
"I think he is certainly one of the best in the world and people are right to make comparisons with Diego Maradona," Stuttgart coach Christian Gross told a news conference.
"It's amazing when you think he is still only 22-years-old. He's just a fantastic player."
Argentina forward Messi also earned effusive praise from Barca coach Pep Guardiola.
"The best players are always in the thick of the action," Guardiola told a news conference.
"(Michael) Jordan did it with the Bulls, (Kobe) Bryant does it with the Lakers and Leo does it here.
"We want him to stay with us because he's the best and we wouldn't swap him for anyone."
Messi's first goal came in the 13th minute when the FIFA World Player of the Year raced at the Stuttgart defence and smashed the ball past Jens Lehmann into the roof of the net.
His perfectly-weighted pass nine minutes later set Yaya Toure free on the left to cross for Pedro to score Barca's second and Messi struck again on the hour with a clinical drive from the edge of the penalty area.
They were his seventh and eighth goals in his last four matches in all competitions.
Barca President Joan Laporta said one of Messi's strengths was his unselfishness.
"The first to promote the spirit of the team is Messi himself," Laporta said in a television interview. "His enormous talent entertains us in key moments, but the whole team performed at a fantastic level."
