HOUSTON(AP) Hunter Pence thought he might have a shot at an inside-the-park home run against Colorado on Wednesday night, but settled for a triple.

He left no doubt in his next at-bat, launching a solo home run to left field. The Houston right fielder also had two RBI singles to continue his sparkling start and help the Astros beat the Rockies 6-4 for their fourth straight victory.

''We have the confidence, we're picking up the urgency and picking each other up as a team,'' said Pence, who has hits in 12 of his last 15 games. ''We're playing every game with everything we've got.''

The game was tied 3-3 in the fifth inning when Pence hit a towering drive off the wall in left-center, missing a home run by a few feet. The ball caromed sideways and Pence was ready to round third and sprint for home, but third-base coach Dave Clark waved his arms to stop him.

The Astros then trailed 4-3 when Pence led off the seventh and he hammered a 2-1 slider from Jason Marquis (7-4) over the railroad tracks in left, his sixth of the season.

''I feel like I have a good approach, I have an idea of what's going on,'' Pence said. ''If I continue to put that bat up there every day, good things can happen.''

Lance Berkman and Ivan Rodriguez also drove in runs for the Astros, who've won five of six overall.

Chris Sampson held the Rockies scoreless in the eighth and ninth to earn his third save in four chances. Houston manager Cecil Cooper said he stretched Sampson for two innings to rest closer LaTroy Hawkins , who'd pitched in the last three games.

''I knew that if anyone was on the back end, more than likely, it was going to be me,'' said Sampson, who dropped his ERA to 1.91. ''I'm having a good year so far, just got to keep it going.''

Tim Byrdak (1-1) pitched a perfect seventh in relief of starter Brian Moehler to get the win.

Ian Stewart hit a three-run homer off Moehler for the Rockies, who've lost four in a row and seven of their last eight games against Houston.

The Astros started the bottom of the first with four consecutive singles off Marquis to build a 3-0 lead.

Leadoff man Michael Bourn scored on Pence's hit and Carlos Lee singled to load the bases. Berkman grounded out, but Miguel Tejada scored and Rodriguez then singled up the middle to drive home Pence.

Moehler allowed only two singles through the first four innings. Brad Hawpe and Seth Smith started the fifth with singles before Stewart drove a 1-0 pitch into the upper deck in right, his eighth homer of the season.

Dexter Fowler doubled to center leading off the sixth, advanced on Clint Barmes ' bunt and scored on Todd Helton 's sacrifice fly to put the Rockies ahead 4-3.

Marquis was mad at himself for allowing Pence's tying homer.

''I made some good pitches and I battled out of some jams,'' he said. ''But I didn't make a smart pitch in the seventh. I shouldn't have let myself get beat by a secondary pitch.''

Marquis then gave up a single to Lee and Randy Flores relieved. Berkman singled, Joel Peralta replaced Flores and Rodriguez lined out.

Geoff Blum then hit a grounder to Helton, who threw to Barmes at second to force out Berkman. Barmes' return throw for the double play skipped away from Peralta, who was covering first base, and Lee scored to give Houston a 5-4 lead. Peralta was charged with an error.

''When you can't get that base hit, and just open up some breathing room, it's like every little thing is magnified,'' Colorado manager Jim Tracy said. ''We drop that ball at first base and we don't take care of opportunities when we have them.''

Pence added an RBI single in the eighth off Manny Corpas.

Notes: Tejada's single in the first inning extended his hitting streak to 17 games, the NL's longest run. It matches the longest hit streak by an Astro since Berkman's 17-game streak between April 30 and May 18 last season. ... Rockies SS Troy Tulowitzki underwent an MRI on his swollen left hand in Houston. Tulowitzki left Tuesday's game in the fourth inning after injuring his hand on a check swing. ... Astros closer Jose Valverde fielded bunts and threw 30 pitches in a bullpen session. Valverde has been on the disabled list since April 28 with a right calf strain. Cooper said Valverde will throw a simulated game on Friday.