Hull midfielder George Boateng could be out for up to three months with knee ligament damage.
The 33-year-old was carried off on a stretcher during last night's 1-0 FA Cup third-round replay win at Newcastle.
Manager Phil Brown told the Hull Daily Mail: "It looks like it could be the medial ligament, the extent of which we're not sure about, but we're possibly looking at two or three months."
He added: "It's a big blow to lose someone with George's experience."
Former Holland international Boateng has made 18 first-team appearances for the Tigers since his £1million move from Middlesbrough last summer.
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