The Cubs' clubhouse was as loud and lively as it has been in several weeks late Monday afternoon as the team prepared to face unbeaten Roger Clemens at Minute Maid Park.

Players were buzzing in and out like a dorm room during final-exams week, Bob Marley was wailing over the clubhouse stereo, and in the center of the commotion, Cubs starter Mark Prior quietly went over his game plan.

A baseball season is a long, slow grind from April through September, and sometimes the days all blend together.

But every once in a while comes a dream matchup like Clemens vs. Prior that makes even the most road-weary player step back and take a deep breath.

That pregame energy carried over to game time Monday, as the Cubs knocked out Clemens with a 7-2 victory, ending his perfect season after nine straight wins.

Prior threw five shutout innings, while Todd Walker homered twice, tripled and tied a career high with four hits, moving the Cubs within two games of first-place St. Louis in the NL Central.

Clemens (9-1) fell to 1-2 lifetime against the Cubs, including a 5-2 loss to Kerry Wood on June 7, 2003, at Wrigley Field. The loss ended Clemens' 13-game win streak, dating back to Sept. 11, 2003, when he pitched for the New York Yankees.

Despite the emotion of the moment, Prior downplayed its significance.

"Obviously going against somebody who's going into the Hall of Fame in five years or whenever he retires, it's always nice to beat him," Prior said. "I think if it was a situation like last year when Woody was throwing against him, and it was kind of a one-time deal ...

"But I'm going to face him again, hopefully. Tonight for me was more personal. I wanted to really make some improvements off my last outing. It was more of determination, kind of a personal battle with myself."

Prior allowed five hits with eight strikeouts in his second dominant start since his comeback. Prior earned his first victory since beating Florida in Game 2 of the National League Championship Series last Oct. 8. It was his first regular-season win since Sept. 27, when he stopped Pittsburgh in the opener of the Cubs' division-clinching doubleheader sweep.

"I know he was focused," manager Dusty Baker said. "I knew this was good for him, to face Roger Clemens on ESPN, and Roger going for his 10th victory. We knew he was going to rise to the occasion."

Clemens gave up five runs on 10 hits in six innings, never finding a groove.

"I was battling all night," Clemens said. "My stuff seemed like it was good enough. But after a while everything was up in the zone, and I paid for it."

The Cubs opened the scoring in the third on Walker's two-out triple that rolled up the center-field hill and an RBI single by Ramon Martinez. Aramis Ramirez opened the fourth with an opposite-field homer, and the Cubs added two more in the fifth to put Clemens on edge. He began muttering under his breath on a walk to Moises Alou in the fifth.

Walker hit the first of his two home runs in the sixth, in Clemens' final inning. He's now 14-for-34 against Clemens in his career.

"To me, it's more concentration than anything," Walker said. "Probably I've got more respect for him than anybody."

Prior was removed after reaching 92 pitches, and left-hander Jimmy Anderson threw three shutout innings before giving up a pair of runs in the ninth. Baker said Sunday's 15-inning win over Anaheim did "a lot for our psyche and our confidence" heading into Monday's game. It showed as the Cubs won for the fourth time in five games.

"Had we lost that game, who knows how we would've felt [Monday]," he said. "Everybody was kind of running on fumes."