Newcastle United defender Steven Taylor is likely to miss the rest of the season as he prepares to undergo surgery on his injured Achilles tendon.
The 25-year-old centre-back limped off during the second half of Saturday's 3-0 Premier League defeat by Chelsea at the Sports Direct Arena.
A club spokesman said: "After medical assessment, he will be having surgery on Monday.
"It is likely he will be out for the rest of the season."
Taylor's central defensive partner Fabricio Coloccini also came off injured during the first half of the match with a thigh strain. He is a doubt for next weekend's trip to Norwich.
Newcastle manager Alan Pardew had been able to field the same back five in each of the club's 14 league games to date this season.
Their other recognised senior centre-back Mike Williamson is still recovering from a broken arm and an ankle problem.
Full-back James Perch is likely to fill in in central defence and may be joined by right-back Danny Simpson, with new signing Davide Santon possibly coming into the starting XI.
Despite the defeat by Chelsea, the Magpies currently have the fourth best defence in the top flight having conceded only 15 goals this term.