Newcastle and England striker Michael Owen has broken a bone in his foot and will be out for two to three months.
The 26-year-old fractured his fifth metatarsal during the Magpies' 2-0 defeat at Tottenham on New Year's Eve.
"It's a mighty blow," said boss Graeme Souness. "It's an absolute disaster for him and an absolute disaster for the club. It's a dark day for us."
In a further piece of bad news for the club, keeper Shay Given has suffered a suspected broken thumb.
St James' Park boss Graeme Souness bought Owen for £17m from Real Madrid in August.
He has been an instant hit alongside captain Alan Shearer up front, scoring seven goals in nine starts, so this injury is a setback for Souness.
England coach Sven-Goran Eriksson said he would be monitoring Owen's recovery closely ahead of the 2006 World Cup.
"Obviously I'm very disappointed for Michael," Eriksson told the Football Association website.
"It's very bad luck for him and for Newcastle United.
"Michael is a fantastic striker and a very important player for his club and
"I hope that he returns to fitness as soon as possible and I will follow his
progress very closely."
Newcastle assistant manager Alan Murray added: "(The injury) might have to be pinned which will prolong the recovery. We're hoping that it won't have to be but we will have to have a look when it settles down.
"We're looking at eight to 10 weeks if things go well, longer if they don't.
"We've been riding along between 14th and 10th for most of the season and if you lose somebody with Michael's goalscoring ability it's a blow to anybody and something we could well do without."
The fifth metatarsal is the bone in the foot that connects to the little toe - and the same one broken by England colleagues Gary Neville, in April 2002, Steven Gerrard, in September 2004, and Wayne Rooney in Euro 2004.
David Beckham broke his second metatarsal just before the 2002 World Cup, and was still struggling for fitness during the tournament.
Republic of Ireland international Given has been one of Newcastle's most consistent performers this season.
It is unclear at this stage what injury the keeper has suffered.