Messi was harried, hounded and pushed by the Milan defenders who often used a rotation system, where defenders take it in turns to give away free-kicks, to bring his trademark runs at the heart of their defence to an abrupt end.
Despite playing at home and managing only 38 percent of possession, coach Massimiliano Allegri was delighted with Wednesday's 0-0 draw and, above all, the commitment of his side.
"I've always said that I'm lucky enough to train a great group of professionals and even the players who aren't on the pitch, even the ones who watch from the stands, they're always ready when they're called upon," he said.
Midfielder Massimo Ambrosini, standing in for the intimidating Mark van Bommel in midfield, Luca Antonini and 36-year-old Alessandro Nesta, who replaced the injured Thiago Silva at the heart of the defence, were excellent as Milan, seven-times European champions, held firm.
Nesta seemed happy to accept a yellow card as the price for ending one of Messi's runs and Milan believe they can sneak an away goal next Tuesday.
"This draw should give us trust and courage," said Ambrosini. "There was the right spirit tonight, before, during and after the match. We'll go to Barcelona with trust in ourselves.
"The squad deserve praise, as do the fans. We'll have the same spirit there as well. We have to be honest, we're facing a team that has defined their era of football but we'll go there and play."
EQUAL TERMS
Ambrosini himself was showered with praise by his team-mates.
"Ambrosini was a real gladiator, he fought for every ball both in defence and attack," said Antonini, who had something of a journeyman career, being loaned from club to club, before he joined Milan in 2008.
"I saved a goal from Alexis Sanchez as I had the timing and the reflexes to slide in on time and take the ball away from him. It was a bit of skill and a bit of luck.
"We faced them on equal terms and that gives us the strength to go to the Nou Camp and play for a place in the semi-finals."
When Barcelona did get through, they were foiled by Christian Abbiati who pulled off several outstanding saves in the Milan goal.
Messi also had to struggle with a dreadful San Siro pitch, at one point slipping as he went to take a free-kick. His frustration appeared to boil over with an uncharacteristic late tackle on Clarence Seedorf, for which he was lucky to escape a yellow card.
Barcelona are expecting to face more of the same at home next week, knowing that if Milan can sneak an away goal they face a struggle to retain the title.
"We know how experienced they are, they have a lot of clever players so I think the next game will be the same because they defend so well," said Barcelona defender Javier Mascherano.
"But we have a lot of players in attack that can put on a good show, score goals and win us the match."
