AC Milan could welcome Mario Balotelli back to the fold for their Champions League clash against Barcelona when the Italian giants will take inspiration from struggling Spanish league side Osasuna.

Balotelli is one of six Milan regulars to have been sidelined by injury recently and was expected to sit out Tuesday's Group H fixture at the San Siro due to a thigh problem.

However the 23-year-old striker, whose last game was for Italy in their final World Cup qualifier against Armenia last week, is on the mend and could make an appearance, according to Milan coach Massimiliano Allegri.

"We will evaluate him following training later today," Allegri told reporters at the club's Milanello training complex outside of Milan.

"He's definitely improving. In the afternoon we'll see if he's fit enough for selection or not."

After an opening win over Celtic and a draw away to Ajax, the latter earned when Balotelli won and scored a penalty in the fourth minute of second-half injury time, Milan sit second in Group H on four points.

Barcelona have won both of their opening games, at home to Ajax (4-0) and away at Celtic (1-0), but the Spanish giants have arrived in Milan days after suffering a setback in La Liga.

In what may be construed as a boost for Allegri's depleted side, Gerardo Martino's side were held to a scoreless draw by Osasuna on Saturday -- the first time they had failed to score in the league since January 2012.

Osasuna sit third from bottom of the Spanish top flight, and Allegri added: "Milan are no worse than Osasuna."

However the Italian, echoing the thoughts of Brazilian playmaker Kaka - who returned from injury during Saturday's 1-0 win over Udinese - called for a disciplined, collective display to counter Barca's typically strong possession game.

"We have to stay extra focused, especially while defending because they will surely enjoy more possession against us, as they do against all the teams in the world," said Allegri.

Barcelona will make their fourth visit to the San Siro in as many seasons, having accounted for the Italians in the group stages in 2011, in the quarter-finals in 2012 and in last season's last 16 knockout phase.

Having seen his side routed 4-0 in the second leg at the Nou Camp last March, Allegri knows it will take a special performance to seal a morale-boosting win.

He said: "We can afford to go out and take an audacious approach because we're still not in the direct elimination phase.

"But to get the result we want, we all need to have the same mindset. If we don't play as a team, we will lose."