Lidge had an MRI exam last week and is day to day. He had two operations on the knee before last season, but hopes to avoid the disabled list.
"We're trying to get rid of it as fast as possible," Lidge said Monday night. "It's frustrating, but I missed a few games last year at the start of the season, and when I came back I felt great. If I have to do the same thing this year, miss a couple of games, that's OK."
Lidge converted all 48 save opportunities (including the postseason) last year while helping the Phillies win their second World Series title.
He said he started feeling discomfort in his knee during the April 10-12 series in Colorado. It's the same knee Lidge had surgically repaired twice before the 2008 season. He had torn cartilage fixed Oct. 1, 2007, then had his meniscus repaired on Feb. 25, 2008.
The right-hander got an MRI on April 20, which Lidge said revealed no tears. He had a cortisone shot a few days after that.
"The MRI showed some swelling, nothing structural," Lidge said. "That being said, there's some discomfort when I pitch."
Such discomfort would help explain Lidge's mechanical issues and spotty control during the first month of the season, when saves haven't come easy. In Florida on Saturday night, he loaded the bases before getting a 34-pitch save.
"If we nip it in the bud, hopefully it will be resolved for the rest of the year and it's something I won't have to worry about," Lidge said. "[After Colorado,] it just sort of gradually got worse. I kept throwing and now we're at the point where we have to make sure it doesn't get any worse."