BUFFALO (AP) — Buffalo Sabres defenseman Mattias Samuelsson is out indefinitely with a lower-body injury, coach Lindy Ruff said Wednesday.

Ruff called the severity of the injury “pretty strong.” He didn’t specify the nature but said Samuelsson is not expected to need surgery.

Samuelsson was hurt in a 7-5 loss to Montreal on Monday, when a Canadiens player rolled up on his leg. It was Samuelsson’s first game back after missing three as a healthy scratch in Ruff’s bid to shake up his roster.

Ruff listed leading scorer Tage Thompson and goalie Ukko-Pekka Luukkonen as day to day, with both having an opportunity to play Thursday, when Buffalo hosts the St. Louis Blues. Thompson also did not return to the game Monday after sustaining a lower-body injury.

Luukkonen started against Montreal despite dealing with what Ruff called an ailment, and he was pulled after allowing four goals on 18 shots through two periods.

By placing Samuelsson on injured reserve, the Sabres filled the roster spot by claiming goalie James Reimer a day after being placed on waivers by Anaheim. The 15th-year player returns to Buffalo after losing him to a waiver claim by Anaheim on Oct. 7. Reimer allowed nine goals in losing two starts with the Ducks.