CHICAGO -- Saying his left knee had "turned the corner," Astros first baseman Lance Berkman is scheduled to make two rehabilitation appearances at Triple-A Round Rock on Saturday and Sunday after being cleared to appear in a game Friday by team medical director Dr. David Lintner.

Berkman, who didn't travel with the Astros on their six-game road trip to St. Louis and Chicago, has been working out in Houston. He has yet to appear in a game this season after undergoing arthroscopic surgery March 13 to clean out loose cartilage in his left knee.

"I'm glad to be making some progress and am finally good enough to go out and see how it does in a normal game," Berkman said in a phone interview with MLB.com. "I'm very hopeful."

Berkman worked out in Houston with physical therapist Matt Holland and alternated daily between baseball activities such as running and taking ground balls and strength exercises.

"It was really the first week it showed noticeable improvement on a daily basis," he said. "I think it's turned the corner and it won't be long. I'd like to be able to play Tuesday [against Florida at Minute Maid Park]. The first step is playing in a couple of games."

When asked if there was something with his knee he felt he'd have to be comfortable with in a game situation before returning to the lineup, Berkman didn't have anything specific in mind.

"It's more of getting out there, getting in game situations of all different types and the movements you have to execute over the course of a game," he said. "I think we'll see how it responds and just go from there. I just need to test it out and see how it is."

Berkman has been watching the Astros closely from Houston, and he was thrilled to see his teammates pull out their first win of the season Thursday in St. Louis after an 0-8 start.

"That's what we needed, for sure," Berkman said. "It's good to get that monkey off our back, and now we need to have a good series in Chicago."

Berkman hit .274 with 25 homers and 80 RBIs in 136 games last year with the Astros and missed 18 games with a strained calf. He ranks in the Top 10 in every major offensive statistical category in Astros history, ranking second in home runs, and third in RBIs, walks, doubles, runs and total bases.