The move is more precautionary, and Lilly (12-8, 3.02 ERA) is expected to start one of the Cubs' games this weekend in San Francisco. The left-hander underwent arthroscopic surgery on his left knee in late July, and was 3-1 with a 1.53 ERA in seven starts since he returned Aug. 17. Lilly has struck out 36 in 47 innings in that stretch while walking eight.
"If we needed him to pitch Wednesday, he would've pitched," Cubs manager Lou Piniella said.
Piniella also said Rich Harden, who was to have pitched Monday against the Brewers but was being passed over to give him a chance to rest, will likely start this weekend against the Giants as well. Harden (9-9, 4.09 ERA) had failed to get past four innings in his last two starts.
Samardzija made his first Major League start Aug. 12 against Philadelphia, giving up seven runs on eight hits over 3 1/3 innings while striking out four. The right-hander, who was the Cubs' fifth-round pick in 2006, has split time this season between the big league team and Triple-A Iowa. For the season, he's 1-2 with a 7.89 ERA in 19 games with the Cubs.
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.