Lidge, who after his outing on Thursday said his slider "stunk," pitched to Brooks Conrad and Hunter Pence in a simulated setting.
"I wasn't real satisfied with how my slider was coming out last game, so I wanted to do a little work on one of the back fields to get to where I feel comfortable," he said. "That's the luxury of Spring Training. If something doesn't feel great, you can go and hammer it out. Fortunately, it's a nice thing to be able to do."
Lidge allowed three runs on two hits while walking two over one inning of work last week against the Marlins, his worst outing since his first spring appearance when he yielded four runs over one inning.
Lidge threw mostly sliders during Sunday's simulated session but threw his fastball, too.
"I treated it kind of like a game," he said. "I wanted to throw more sliders than I normally would in a game, which is why we did it here."
"He wanted to work on the release point with his slider," manager Phil Garner said. "Try to get his arm angle in the right slot, get a good release point. Having live BP, I think that's a good thing. You can see reactions from hitters and it gives you a little better feedback than just a bullpen."
Lidge's next outing will be on Wednesday when the Astros host the Devil Rays.
Pitching change: Jason Jennings was scheduled to start the Astros' game in Jupiter on Monday, but instead, he'll pitch in a Triple-A game in Kissimmee while the team is on the road.
Fernando Nieve will start the game against the Marlins in Jennings' place.
With so many pitchers needing work and not enough Major League innings to go around, occassionally, pitchers are relegated to Minor League games. Woody Williams made two starts against Minor Leaguers this spring, and relievers Dan Wheeler and Trever Miller have also worked in "B" games.
Jennings had previously told management he'd rather stick to Major League games, but he doesn't mind working on the back fields Monday.
"If we have guys that need to get innings in, I don't mind coming over here, as long as I'm getting my pitches in," he said. "I still have two more [spring] starts after tomorrow, so it's fine. As long as I'm getting my pitches in, that's all I'm worried about."
Oswalt dealing: Games that Roy Oswalt starts usually don't last very long, and the right-hander's outing on Sunday was typically efficient.
Oswalt worked quickly against the Blue Jays, tossing 5 2/3 innings in a game that lasted two hours and 11 minutes. He also hit twice as many batters as he allowed hits, plunking two Blue Jays hitters while yielding one hit -- a double by Reed Johnson with one out in the sixth frame.
"I threw a lot of changeups," Oswalt said. "The last double was a changeup. I put a little too much on it. He was still out in front -- it looked like he was swinging for a fastball, but he still stayed back long enough to hit it fair."
Oswalt threw 71 pitches and hopes to increase that to 100 during his next start, slated for Friday in Winter Haven, where the Astros and Indians will play a night game.
Everett hitting second: Just as he did with Brad Ausmus two days ago, manager Phil Garner slotted Adam Everett in the two-hole on Sunday for the Astros' game with the Blue Jays.
Garner doesn't have plans to hit Everett second during the regular season. He just prefers to give the shortstop an extra at-bat per game, to make up for the two games Everett missed for precautionary reasons regarding his lower back.
"He's on the short end," Garner said. "He and Ausmus, I'm trying to make sure they get the at-bats."
Ideally, Garner would like for all of the hitters to have 55-60 at-bats by the end of Spring Training. Everett has 27, while Ausmus has 21.
Alyson Footer is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.