Pato damaged his left ankle shortly after scoring in Sunday's 1-0 Serie A win against Fiorentina.

"I have spoken to the doctors," said AC Milan vice-president Adriano Galliani.

"Our hope is to have him available for the game in London."

Pato's unavailability over the next few weeks is a major blow to Rossoneri coach Carlo Ancelotti as the 18-year-old has made a sensational start to his San Siro career, scoring four times in six appearances.

Ancelotti did receive some good news on Tuesday, however, with key midfielder Gennaro Gattuso set to return next week after time on the sidelines with a thigh injury.

"Gattuso has a thigh problem," said Galliani. "We will have to speak to the doctors but we hope to have him back next week."