AC Milan are sweating over the fitness of striker Marco Borriello ahead of their Champions League clash against Olympique Marseille.

Borriello is struggling with a knee injury and is doubtful for tomorrow's Group C encounter at the San Siro.

The Italian forward was the inspiration behind his team's 4-3 triumph against Cagliari at the weekend, scoring a goal and earning a penalty.

That result marked Milan's fourth win in five games, keeping Leonardo's side third in the domestic standings, seven points behind Serie A leaders Inter Milan.

The Italians go into Wednesday's game level on seven points with Real Madrid with two Champions League group games left to play. Marseille are just one point behind them.

Both sides know that victory would put them a step closer to the last 16.

"Sunday's triumph was extremely important for the team to be able to focus on the game against Marseille with our head held up high and in fine spirits," said AC Milan defender Thiago Silva.

"We must play against Marseille with calmness, just as we did against Real Madrid.

"We cannot go out on the pitch desperate to break the deadlock in the first 15 minutes but rather be patient.

"Just like us, Marseille know that this game is crucial and it will be a difficult test."

French defender Mathieu Flamini is desperate to recover from an ankle injury in time to face his former team on Wednesday night.

Flamini missed the clash against Cagliari but could be given some playing time on Wednesday.

"I hope I can play," he said. "It's always special for me to play against OM.

"It is the club where I grew up, that I love.

"Tomorrow's match is an important game for both teams.

"A win tomorrow would avoid us having any additional pressure in our last group game.

"My hope is that both teams qualify for the next round."

A draw would not be a bad result for the hosts considering they take on FC Zurich in Switzerland in the final group match. However, OM will be desperate to claim a win as they face a more challenging game at home to Real Madrid next month.

Didier Deschamps' side travel to the San Siro in good spirits after moving to fourth in Ligue 1 with Friday's 1-0 win over fierce rivals Paris St Germain, courtesy of a Gabriel Heinze goal.

The French giants ended a run of six straight away defeats in the competition with a win at Zurich last on October 21.

The hosts welcome back defender Alessandro Nesta from suspension while they are without injured trio Marek Jankulovski, Gennaro Gattuso and Oguchi Onyewu.

Leonardo is set to field the attacking trio of Ronaldinho, Alexandre Pato and Borriello in attack.