But will The Rocket be ready for liftoff when he faces the Chicago White Sox on Saturday night at U.S. Cellular Field?
With temperatures for Game 1 expected to be in the low 50s and Clemens having battled a tweaked hamstring and a backache in recent weeks, whether or not the 43-year-old is in top form will be critical for Houston.
Clemens pitched well in his last National League Championship Series start on Saturday in Game 3, and he contributed three outstanding innings in a relief appearance in the clinching game of the NLDS against Atlanta.
In both of those appearances, it was much warmer than the predicted temperature for Saturday's 7:29 p.m. CT first pitch.
"I don't really care," Clemens said. "I think the only time that I have a problem on the mound or on the golf course is when there's too much wind. I can handle the hot and the extreme heat, and I don't mind if it's freezing cold -- just have to keep your body ready.
"We're fortunate as pitchers, because we're involved in every pitch; our bodies are doing something and moving. It's nice. That means you're playing late in the year, when you start getting cool weather, so it's nice to be a part of that."
The back and hamstring are fine, and Clemens and the Astros are confident he won't have any problems with either as long as he warms up properly.
"I don't know that it really matters. I'm getting the ball to go out tomorrow to get something done -- to get this thing started, to get it started in a positive way for my ballclub -- and I plan on doing it," Clemens said. "That's the bottom line. I don't care how my body feels this time of year. If you need more aspirin, if you need more heat, if you need more ice, this is the time you get it. And you don't ask questions."
Clemens is so methodical in his preparations that the Astros aren't concerned about the seven-time Cy Young Award winner.
"Roger's fine. He's fine, he'll be able to go," Astros manager Phil Garner said.
Clemens went through his normal day-before-the-game routine Friday afternoon. The right-hander also checked out the ballpark where he has posted a 4-3 record with a 3.94 ERA in 10 career games.
"I'll be prepared and do what I need to do," Clemens said. "Really, it comes down to what I've told you every time. I'll go out and see how my body feels, and I'll make adjustments from that point on."
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For Clemens, it will be his eighth World Series appearance, all starts, and his first since 2003 when he started Game 7 for the Yankees against the Marlins. He said he was excited to be get the opportunity to pitch the first game for a Texas team in the World Series.
"I think, over the last couple of days, once we caught that fly ball in St. Louis, I've just reflected on everything that's happened a little bit and just to see the expressions on the guys' faces that have been here, I'm most happy for them," Clemens said. "I'm thankful that it's happened for them so they get the experiences, because not every great player gets the opportunity to do this. Not every player that just has an average career or just a fairly average career, they don't get to experience this type of excitement and this type of fine alternative to the situation, where everything is magnified.
"But I can tell you everybody is excited at home. It really gets you amped up again, as a player. I'm in that mode where it's working for me. I'm excited about it. I ponder to myself, 'This could be my last couple of starts or your last one.' I'm trying to get everybody that wants to be a part of this and really share it with everyone. And that includes the entire city -- that's the reason I came home. Everybody can say what they want, but it was a real hard decision for me to continue to play, because I felt I touched just about every aspect of this game that I could."
With 19 years in the American League, Clemens probably has a better knowledge of the Chicago roster than most of his teammates, with the possible exception of Andy Pettitte. Clemens has faced some of the Sox before, like Scott Podsednik last year when he was a member of the Milwaukee Brewers.
Other Sox regulars, like Jermaine Dye, Paul Konerko and Carl Everett, have crossed paths with Clemens over the years.
"There's some guys I have faced, there's some other guys that I don't know," Clemens said. "It will be how I feel coming out of the bullpen. You have guys that have hit well past you before, but each time is a new time. I don't put much stock in it either way.
"My body will have to feel good and my stuff will have to feel sharp. I'll have to feature all over the entire zone like I expect to do. If I'm having problems with one spot or another, [catcher] Brad [Ausmus] and I will make the adjustment and we'll go from there. It never changes. It is what it is."
Jim Molony is a writer for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.