Brentford striker Scott Hogan has suffered further significant damage to the injured knee which has kept him out of action since August.
The 23-year-old had been taking part in drills with the first-team squad in the past few weeks, having made encouraging progress after reconstructive surgery.
But during one session, Hogan caught his foot in the turf while passing the ball and will now have to undergo another operation.
It is another major blow for Hogan, who has played 32 minutes in a Brentford shirt after signing from Rochdale in the summer.
He made his Bees debut as a substitute against Fulham in the League Cup but was then carried off 16 minutes into his full debut against Rotherham.
Brentford boss Mark Warburton said: “”It happened during an innocuous passing drill on Tuesday and there was no-one near him.
“This is a devastating blow for a young guy that has worked so hard over the last eight months, along with the medical team, to get back to full fitness.
“Scott has been taking part in technical practices and passing drills and it has been a delight to have him back.
“Scott is a top lad and a top talent and I have no doubts that he will enjoy a first class career.”
Neil Greig, Brentford’s head of medical, added: “At this stage, the timescales for recovery are difficult to predict and I would anticipate knowing more on that front following surgery, which is likely to take place next week.”
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This post was last modified on 24/04/2015