Reds outfielder Jay Bruce may need surgery on his sore left knee, reports John Fay of the Cincinnati Enquirer. He was scratched from Sunday's lineup. The nature and extent of the surgery, as well as a potential timetable, are unclear.

Bruce, 27, has hit .218/.355/.366 (99 OPS+) with only three home runs in 29 games this season. He has been an ironman for Cincinnati in recent years, playing no fewer than 148 games each year from 2010-13.

Obviously losing Bruce would be a big blow to the Reds despite his slow start. He is their only lefty power bat aside from Joey Votto, and center fielder Billy Hamilton (knuckles) is banged up as well. Bruce was the sure thing in the team's outfield.

The Reds have not provided any update on Bruce's status since he was scratched before Sunday's game.