SAN FRANCISCO -- The Padres starting rotation took another hit on Saturday, when the team placed veteran left-hander Shawn Estes on the 15-day disabled list after he fractured the tip of his left thumb.

Estes suffered the fracture Friday after falling down the stairs that lead from the visiting clubhouse to the dugout at AT&T Park during the Padres' 7-3 victory in 13 innings over the Giants.

"I just fell ... I stepped wrong," Estes said. "I put my hand down to catch myself and my body weight came down on my thumb. I don't know how it happened."

Estes becomes the third member of the Padres rotation to land on the disabled list. Jake Peavy (sprained right elbow) and Chris Young (nasal fracture) have also landed on the DL this month.

The Padres have reinstated right-handed pitcher Carlos Guevara from the disabled list to take Estes' spot on the 25-man roster. Guevara, acquired in the Rule 5 Draft in December, was with Triple-A Portland, where he threw six scoreless innings.

Estes, who was 1-1 with a 3.33 ERA in five games (four starts), missed the entire 2007 season after having Tommy John elbow reconstruction surgery in 2006.

Estes made his season debut for the Padres on May 8 in Atlanta and had given the team a lift after replacing right-hander Justin Germano in the rotation.

"It's borderline depressing," Estes said before the start of Saturday's game against the Giants. "I'm going to stay away from the Golden Gate Bridge for the next couple days."

Estes' thumb was in a splint Saturday. He's scheduled to see a hand specialist when the Padres return to San Diego on Monday. Estes is hopeful there is no ligament or tendon damage to the thumb.

San Diego manager Bud Black hasn't announced who will start on Monday, when the Padres face the Cubs at PETCO Park. That would have been Estes' turn to start.

The most logical candidate would be Cha Seung Baek, who was acquired last week from the Seattle Mariners. Baek made his Padres debut on Friday and struck out the side in his lone inning of work.