With Houston's typical rotation, Clemens would be an option for Game 5 on Thursday at Minute Maid Park in Houston. If the right-hander is unable to pitch, Purpura said left-hander Wandy Rodriguez or right-hander Ezequiel Astacio are options.
"One of the things that we did which proved to be a positive is that we went with 11 pitchers on the roster, so we've got some versatiliity there," Purpura said. "I would be hard-pressed to say you could bring back [Andy] Pettitte on short rest, but you never know. I mean that's not something we would look to do at this stage. Really it's way too far ahead. I'd say Astacio and Rodriguez would probably be the best options at this stage."
Purpura said the fact that Pettitte is coming off elbow surgery and has pitched well over 200 innings are factors that would make the left-hander an unlikely short-rest option.
In any case, the GM isn't going to go too far down that road until he must.
"[There will be] no decision-making process until we get closer to [Clemens'] next start," Purpura said. "When it comes to Roger Clemens, I have to be optimistic. This guy has gutted out a lot of things through his career, in big games, so I certainly would not count him out. This is a guy who heals very well. I wouldn't count him out.
"Roger's got a PhD on his body in terms of what he needs to do and when he needs to do it. I'm not counting him out until he says he can't do this and I don't think that he will until it's close to his next start."
Purpura noticed the impact the injury had on Clemens by watching the right-hander's split-fingered fastball. With the splitter, a pitcher needs to get out in front of the pitch and fully extend. Clemens was unable to extend fully after the second-inning injury. The injury is the same one that caused him to miss a start in August.
"I guess the fact that it's the same hamstring, anytime it's more than once, it becomes almost like a chronic situation," Purpura said. "You get some scar tissue in there and that type of thing and it's not optimum."
Clemens pitched only two innings Saturday, his shortest World Series start in eight games. He threw 54 pitches, including 35 for strikes, but was noticeably limping when he left the field following the inning.
Clemens underwent treatment during and after the game. He left the ballpark after making a brief statement to the media.
"I had the problem in the second inning, and fought my way through that inning, got through that inning," Clemens said. "I came up here [to the clubhouse] and as quick as I could to take my sleeve off and have them check it and see if there was anything I could do so I could continue. And the fluid already started to build up in my leg. So they gave me some medication and I'm going to treat it, and that's all I can tell you from there."
The 43-year-old Clemens became the oldest pitcher ever to start Game 1 of the World Series when he took the mound at U.S. Cellular Field.
"By no stretch of the imagination am I counting him out now," Garner said. "We'll go day-to-day with it to see how it is."