DETROIT -- Roger Clemens retired the first seven Detroit batters he faced on Tuesday night and shut down the Tigers for 6 1/3 innings in his second start of the season at Comerica Park.

The problem was, his counterpart, Tigers starter Nate Robertson (8-3), matched Clemens' outing with a seven-inning shutout of his own for his third win in as many decisions, as Detroit took the second of the three-game series with a 4-0 win.

"[Robertson] pitched very well. He did a great job," Astros manager Phil Garner said. "We just haven't been doing a good job recently coming up with big hits when we needed them. We have put some runs on the board but we have not gotten our big hits."

Only three Houston runners reached as far as second base on Tuesday night and none did so before the fourth inning. Robertson retired the inning's first batter, Jason Lane, on a grounder to third. Morgan Ensberg followed with a walk before Lance Berkman singled to center and Ensberg went to second. Ensberg would advance no further, however as a result of Chris Burke's strikeout combined with Ensberg's caught stealing at third to end the inning.

The Astros did not have another baserunner reach second for two more innings until Craig Biggio sped to second base on Robertson's full-count wild pitch. That threat ended with Burke once again when the second baseman grounded into a force out to end the sixth.

Meanwhile, Clemens, who threw 84 pitches and 50 for strikes, did his part until he was relieved by Dan Wheeler following a pair of one-out walks at the beginning of the seventh frame.

"Obviously, my last start, I had to come out of that one because of the pitch count," Clemens said. "It was definitely a focal point for me to get strikes and to be aggressive in the zone."

Still, Clemens was glad for his improvement from last Thursday's season debut when he pitched five innings and allowed two runs on six hits to the Twins.

"My legs are getting stronger to where I feel I can get the ball to the plate," Clemens said. "Tonight was great. I was within two or three balls of everywhere [catcher Brad Ausmus] and I wanted to throw as far as location. That's definitely an improvement. We were working well together. Brad and I had a pretty good game plan. We stuck to it and it was working for the most part."

Part of Clemens' plan was to keep pitching in the seventh inning, but Garner decided to make the call to the bullpen.

"The skipper came out and talked to me, and I was hoping at that point that he would give a chance to get through that inning and maybe get to the eighth," Clemens said. "I'm here for a number of reasons, but I have to eat up some innings, too. I don't want to see our bullpen guys out there all of the time. We've asked these guys to do so much for us over the last two years, let alone already this year. To give them a break here or there, that's our job as starters."

Wheeler tried to do his job in support of the Astros starter but could not.

Facing his first batter and a 2-2 count, Wheeler gave up an RBI double to Detroit's Craig Monroe. The play didn't end with Monroe's hit, either.

Left fielder Preston Wilson fielded the ball off the top of the fence, throwing the ball into cutoff man Adam Everett, who ran into more trouble when he made a wild throw in an attempt to get Monroe out at second base. Instead, Everett's misfire went past Burke, the Tigers scored their second run and Monroe went to third.

The forgettable seventh inning worsened when Ensberg bobbled Chris Shelton's potential inning-ending grounder at third base and Monroe crossed home plate for a 3-0 Detroit lead.

Detroit's Alexis Gomez entered the game as a defensive replacement in the top of the eighth but became an offensive replacement in the bottom of the inning when the left fielder hit the first home run of his Major League career.