Bolton's Stuart Holden is expected to be out of action for six months after a follow-up operation on a knee injury revealed cartilage damage.
The 26-year-old underwent a "routine procedure" on Wednesday on the knee which he injured against Manchester United last season.
The USA midfielder wrote on Twitter: "Floored, devastated, gutted, just a few words I can think of.
"I will continue to fight and I'm ready for another tough journey."
Holden had only just returned to the Bolton first team after six months out because of the injury.
"It is a big, big blow for Stuart, because he has worked so hard after he sustained the injury, but obviously the most important aspect is to ensure Stuart's well being and that's what we are focused on," said Bolton boss Owen Coyle.
"He went for the procedure and it was picked up that the cartilage was damaged and needed to be repaired, which has now happened, and we will now support Stuart as he begins his recovery."
Defender Jonny Evans was sent off for the tackle on Holden during United's 1-0 victory in March.
Holden made his comeback from injury in Bolton's 2-0 Carling Cup win over Aston Villa eight days ago.
The United States international has suffered an injury-blighted couple of seasons at the Reebok Stadium. As well as the knee injury, Holden suffered a fractured leg while playing for his country in a friendly against the Netherlands last year.