Phoenix, AZ (Sports Network) - Oakland Athletics manager Bob Melvin announced Thursday that closer Grant Balfour will undergo arthroscopic surgery to repair a meniscus tear in his right knee.

The A's expect Balfour to be back in 4-to-6 weeks following Thursday's procedure.

"I feel good about getting it done now," Balfour said in a statement. "It will allow me to get ready for game one of the season."

Balfour experienced some knee soreness near the end of 2012, a season in which he went 3-2 with a team-leading 24 saves and a 2.53 ERA. The right-hander wasn't worried because the soreness went away during the offseason, but an MRI exam taken Thursday revealed the tear.

02/14 12:29:31 ET