Milan vice president Adriano Galliani said he is worried about fatigue hitting the European champions in Tuesday's Champions League last 16 return leg against Arsenal.

Milan have had a punishing schedule since Christmas to make up the two league games they missed while winning December's Club World Cup in Japan and another abandoned in the crowd trouble that followed the police shooting of Lazio fan in November.

"I'm quite worried because we have played more than everyone," Galliani (pictured) said.

"We have had something like 13 matches in 40 days. We are at the verge of the impossible. Let's hope we can find energy from somewhere to face difficult games such as Tuesday's against Arsenal in the Champions League."

The first leg finished 0-0 in London.

The toll of Milan's exertions showed on Wednesday when they were held 1-1 at Catania and slipped out of the Champions League qualification zone to fifth place in Serie A.

"We have to hang in over the next two games before we have a period in which we can work better and manage the injured players better," said coach Carlo Ancelotti.

He added that World Player of the Year Kaka, who extended his contract by two years to June 2013 on Thursday, will miss Saturday's Serie A game against Lazio, but he should be fit for Tuesday after a knee problem.

Defender Alessandro Nesta will also miss the league match against his former club as battles back from a thigh strain, but he should be available against Arsenal.

Ancelotti called on his men to be braver at the San Siro on Tuesday after the goalless first leg.

"We'll have to have more courage than in the first leg, I think the fact they we are playing at home can give us that," Ancelotti said.

Eurosport