Everton striker James Vaughan is set to miss the rest of the season after flying to the USA for a knee operation.
The 19-year will be operated on by renowned knee specialist Dr Richard Steadman on Monday after being injured in training.
Vaughan was out for 12 months from September 2005 after suffering problems with the same knee.
Everton boss David Moyes said: "The knee just locked a couple of times in training and it is terrible luck."
Vaughan has suffered a host of injuries since he became the youngest scorer in Everton's history with a goal against Crystal Palace in April 2005.
He severed an artery in his foot at Bolton last season and missed the start of this campaign after dislocating a shoulder in a pre-season friendly at Preston.
Vaughan has only made one start this season, making another 12 appearances as substitute.
Moyes added: "We don't know yet whether it is the same problem as before but it is the same knee.
"We decided he should have the operation now rather than wait until the end of the season and he has to be a doubt for the rest of the campaign. He is going to go out to Dr. Steadman to have a bit of cartilage trimmed.
"I don't know how long he is going to be out for but he is a doubt for the rest of the season, I would have to say.
"It's a blow to us and to him. We knew that there was something bothering him. We had a look at the knee and we thought it was getting better but then his knee locked again.
"We have decided that we need to have him operated on now. We were hoping that he could get through to the end of the season."
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