ST. LOUIS - All of New England would have been quaking with anticipation. Just imagine: Roger Clemens back at Fenway, wearing the enemy’s colors for a fourth time in the postseason, this time in Game 7 of the World Series.

Five years ago, when Clemens came back in pinstripes to face Pedro Martinez, it was called the most anticipated pitching matchup in the long and quirky history of Boston’s venerable old ballpark. Now, instead of a rematch with Clemens wearing the brick-red jersey of the Astros, it’s just another of those tantalizing baseball “what-might-have-beens.”

Don’t try telling this to the fans in Boston and St. Louis, but a little electricity and even more glamor drained out of the World Series early Thursday night. That’s when Scott Rolen lined a back-breaking, two-run homer off Clemens just beyond the wall in left in the sixth inning to lift the Cardinals to an eventual 5-2 win in Game 7 of the National League championship series.

NLCS Cards 4, Astros 3 Cardinals rock Clemens, reach World Series Pujols does it again for Cardinals More heartache for Series-less Astros Litke: Clemens will be missed in WS Ventre: Big cash ahead for Beltran Postseason schedule More coverage

“When I have a chance to look back tomorrow and throughout the week a little bit, I’ll be extremely happy I didn’t break down this year because I couldn’t afford to do that with the other injuries we had,” Clemens said. “I couldn’t have an off night. You grind and hope it’s good enough.

“I really felt good about our chances tonight,” he said. “It just didn’t work out.”

That the Astros got this far, farther than they had in the 42-year history of the franchise, seemed like small consolation on this night. They were 12 games behind St. Louis in the NL Central when Phil Garner took over as manager for Jimy Williams and 19 1/2 back when they began the improbable run that carried them to the wild-card and past Atlanta in the division series.

Clemens was 10-1 from the midway point of the season, including two wins in the playoffs, and each outing became more important once fellow starters Wade Miller and Andy Pettitte were injured and had to be shut down for the season. The wear and tear on his arm and his nerves, at age 42, was considerable, but he never let it show. Instead, he took the ball every time Garner offered it, determined to see the string play out.

When it did, finally, the memories that came flooding back weren’t about the performances on the mound that could earn Clemens an unprecedented seventh Cy Young award. Instead, they were about the quirky moments that validated his decision to unretire and pitch once more in his hometown just a few weeks after telling after Yankees boss George Steinbrenner that he was through.

Whether he’ll do the same to Astros owner Drayton McLane is anybody’s guess.

“I’ll leave that for later,” Clemens said.

What he chose to remember at the moment was the fans in Houston turning up outside his house at all hours of the night and day, pleading with him to return after the Astros signed Pettitte. He remembered the brief bus rides to different ballparks as the Astros heated up in the playoff chase, filled with bravado and laughs. He remembered his sons getting a chance to see him pitch at home and how, on more than a few nights, he drove home from Minute Maid Park wearing “a funny smile on my face.”

“Even with everything I’ve done in my career,” he said, “this was special.”

Unfortunately, it’s also over.

Pettitte, who pitched alongside Clemens in New York and helped convince him to come back, promised to “try my darnedest” into talking the old man to come back.

“The funny thing,” he added, “is that my biggest worry was that Roger would get hurt and the whole thing would end badly. Instead, he has a Cy Young season and I’m the one who ends up going down.”

For most of the night, against one of the most potent lineups in the game, Clemens looked like his untouchable self. No one in the Cards’ batting order could get around on his splitter or his fastball — he was clocked between 85 mph and 94 mph throughout — and he felt strong. Then came the sixth inning.

“The night was cool, he looked strong and his velocity was still right there. It was a dangerous part of the lineup, some of the best hitters there are against one of the best pitchers of all-time,” Astros pitching coach Jim Hickey recalled. “We had as much confidence in Roger as anybody else we could have turned to.

“How could you not?” Hickey said, “It just turned out that two of them wound up getting the best of him.”

That would be Albert Pujols, who pulled a low fastball into left for a double, and Rolen, who followed that by ripping a shot into the corner. Both figure to be showcase performers when St. Louis, baseball’s winningest team this season, rolls into Fenway to start the World Series on Saturday night.

The Cards are as professional an outfit as there is in the game, solid and patient and efficient, but hardly spectacular. The Red Sox will counter with plenty of hitting, a little better pitching from starters to closer, and plenty more personality.

But the most entertaining pitcher in the game, the guy who came back and defied age and the odds of carrying an undermanned Astros team even this far, won’t be along for the ride.

“I’m sure I’ll watch bits and pieces of it,” Clemens said.

Without the lure of the Rocket back at Fenway for a Game 7, it will be interesting to see how much of the nation does the same.