Kieran Trippier has suffered a broken bone in his foot after the results of a scan showed damage was suffered during the 1-0 win over Aston Villa.
Trippier has hurt his left foot and faces a spell on the sidelines, starting with the trip to West Ham on Saturday.
Newcastle were dealt the hammer blow at the start of the second half when Trippier was stamped on by an opponent.
Eddie Howe said after the game: "Trippier got stamped on and he couldn’t continue with a problem on the top of his foot."
Howe also added that he hoped there would be no break in his foot but his worst fears have been confirmed.
Newcastle are yet to put a timescale on his recovery.
The player is wearing a protective boot and a Newcastle statement read: "Newcastle United defender Kieran Trippier is set to be sidelined for the club's upcoming fixtures after fracturing a bone in his foot during Sunday's 1-0 victory over Aston Villa.
LISTEN: KIERAN TRIPPIER INJURY IS BIG BLOW FOR NUFC
"The 31-year-old scored the game's only goal at St. James' Park to help the Magpies to a third successive Premier League win, but had to be substituted early in the second half after sustaining a foot injury.
"Trippier underwent an X-ray immediately after the game and scans have shown a fracture to the fifth metatarsal bone in his left foot.
"Everyone at the club wishes Kieran a speedy recovery. "
