On Sunday, he was a 43-year-old legend called into relief duty again, this time pitching for the Astros in perhaps the greatest game in the history of his hometown franchise in front of a sellout hometown crowd. To no one's surprise, Clemens delivered.
"He's not of this planet," said Astros general manager Tim Purpura, who watched much of this epic Game 4 alongside another Texas pitching legend, Nolan Ryan. "He's part superhero, part cartoon character."
On Sunday, Clemens was also the last resort.
With the bench empty, the bullpen drained and the Astros locked with the Braves in the longest postseason game in Major League history, the right-hander added to his already Hall of Fame legacy.
Three days after throwing 92 pitches in a Game 2 loss, Clemens worked three shutout innings and was the pitcher of record in Houston's epic, 7-6 win. When Chris Burke's solo home run landed in the Crawford Boxes in the bottom of the 18th inning, it clinched a return engagement with the Cardinals in the National League Championship Series.
"I'm just happy for some of these guys," Clemens said after throwing 44 pitches. "Some of these guys have never experienced this. It's fun to sit back and watch these guys enjoy it. But now we go to the next level."
Throughout the season, Astros manager Phil Garner had jokingly looked at Clemens between starts and asked if he was ready to jump into emergency duty.
As Sunday's game wore on and the Astros staged a stunning comeback to force extra innings, Garner once again gave his veteran the look.
"The look he gave me this time was very serious," Clemens said. "There was no kidding around with it, and so I got out to the bullpen."
Clemens lurked in the back of the Astros bullpen as it slowly emptied. After starter Brandon Backe went Mike Gallo, Russ Springer, Wandy Rodriguez and Chad Qualls. Suddenly the Astros had rallied for a stunning tie thanks to an eighth-inning grand slam by Lance Berkman and a two-out, ninth-inning solo shot by Brad Ausmus.
On to extra innings, and closer Brad Lidge, who turned in two scoreless innings. Then Dan Wheeler, for three.
"I don't really relish what those guys have to go through," Clemens said of the bullpen corps. "Next thing I know, I'm out there by myself. There's not a lot to do; flick seeds, chew gum, talk to the fans. That's about all there was to do."
By the end of the 15th inning, Wheeler was out of gas and the Astros were out of alternatives. Enter Clemens.
"I didn't think he'd be able to throw that many innings today," said fellow starter Roy Oswalt, who won Game 3 to put the Astros in position to clinch. "Next in line was probably me. If it came down to it, I was going to tell them I could throw one.
"I've been watching [Clemens] for two years now and he does things that you just don't commonly see."
In three innings, Clemens allowed one Braves hit -- a one-out double to pinch-hitter Brian Jordan in the 17th. He faced another little jam in the top of the 18th inning when Andruw Jones reached on an error by shortstop Jose Vizcaino, but escaped by striking out Jeff Francoeur, Clemens' fourth whiff of the afternoon.
"He's one of my idols now," said Backe, who was victimized in the third inning by an Adam LaRoche grand slam. "How can you not love the way that this guy plays and the preparation that he goes through? Who knows what was going through his mind out there in the bullpen. He just shut everybody down."
Then Clemens led off the Astros' half of the inning and attacked Braves reliever Joey Devine's first pitch like he was trying to hit it to Dallas. Clemens struck out, but Burke followed with the game-winning home run.
"If [Clemens] would have hit the home run to end the game, I wouldn't have been surprised by that," said Lidge, who joked that he would anoint Clemens the closer until the start of the NLCS. "It's just amazing. It's just standard Roger Clemens at this point."
Sunday was supposed to be Clemens' between-starts bullpen session. He said he felt strong, and the catcher Ausmus, who played all five hours and 50 minutes, said the ageless wonder looked strong.
"His fastball had good finish on it and he hit his spots really well and he stayed out of the center of the plate," Ausmus said. "He actually looked really strong."
"I saw him earlier today and he gave me a little wink," Purpura said. "He said, 'I think I've got a few in me.' I didn't think it would be that many that we'd need him for. He's mythic in my mind."
Clemens credited the home crowd.
"Our place is full, and it's loud, and we love that as [players]," said Clemens, who came out of retirement two years ago to pitch for his hometown team. "For them to come out and wave those towels and get loud, it really motivates us and it's a tremendous home-field advantage, and we really appreciate it."
Adam McCalvy is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.