Ashton has been sidelined since September after he had to undergo surgery on an ankle injury picked up in Zola's first training session.

Initial thoughts were that the striker would be out of action for less than a month, but Zola admits he has no idea when he will have Ashton at his disposal again.

"He had an operation and will wait a couple of months before we can assess him," said the Hammers boss. "He is progressing very well.

"These things are down to the subject, how he reacts and improves. I don't think we'll have him in January or February, but I hope soon.

"He was due to start running on the treadmill and doing rehab with personal physio.

"I spoke to him a couple of days ago and he's happy with the progress.

"I can't say whether he'll be back in March, April, February...it depends how he progresses. I don't know honestly, it is impossible to say so soon.

"He had something causing problems with the cartilage in his ankle but because of his previous injuries it couldn't be a quick thing because they don't want to do any more damage."

West Ham are sorely missing Ashton's firepower.

They have scored only five goals in their past 12 games and Zola admits it is a blow to be without the 25-year-old, who scored twice in the Hammers' first game of the season.

"This is the season so far," added Zola. "I've lost him, probably the best finisher in the team.

"I've had problems at the club and so many things going on. But we'll face it all and we'll come through because we are strong."

It is a massive blow for Ashton too, coming shortly after he made his England debut against Trinidad & Tobago in June.

However, Zola said the player is dealing well with the situation.

He added: "I saw him when we played Tottenham and we spoke there. He was very positive about it."