Rangers goalie Henrik Lundqvist was scratched from the lineup about 90 minutes prior to Thursday's Rangers-Sabers game due to an unspecified illness.
Backup Marty Biron will make the start against Buffalo.
Rangers coach John Tortorella said Lundqvist would be his starter against the Sabres during his pregame address to the media roughly two hours before the teams hit the ice for the 7 p.m. opening faceoff at the Garden.
But shortly after Tortorella's announcement, a Rangers official announced to the media that Lundqvist was being scratched due to an illness and Biron, his backup, would be making his fourth start of the season.
Biron's last start was on Sunday at home against the Blues, when he stopped 20 of 21 shots in the Rangers' 2-0 loss. (St. Louis scored an empty netter late in the third.)
Overall, Biron is 1-2 with a 2.37 goals against average and a .901 save percentage in three starts.
Lundqvist is 6-5-1 with a 2.68 GAA and .918 save percentage in 12 starts.
Biron, a 13-year veteran, signed with the Rangers in July to provide a veteran backup for Lundqvist, who has taken on a sizeable workload for the Rangers in past seasons.
The 33-year-old Biron will face the team that brought him into the league on Thursday night; Buffalo drafted Biron with the 16th overall pick in the 1995 draft.
Biron is one of four players in NHL history to play for all three New York hockey teams (Pat LaFontaine, Mike Donnelly and Jason Dawe are the others).
Lundqvist will miss a start on the same night that sniper Marian Gaborik makes his return for the Rangers. Gaborik, who led the Rangers with 42 goals last season, has missed the past 12 games with a left shoulder separation.