Fighting through lower back stiffness for the third consecutive start, Penny nonetheless helped extend the Dodgers' win streak to six in an 8-1 victory over the Colorado Rockies Tuesday night.

Penny raised his personal record to 5-1 after winning just seven games last season while on the comeback from a nerve injury. He lowered his ERA to 2.31, second-best in the league. But it was an ordeal, requiring 104 pitches over only five scoreless innings, even though he walked just one, struck out five and allowed four hits.

Penny left the clubhouse with old X-rays in hand to take to the office of back specialist Dr. Robert Watkins for a Wednesday examination. The right-hander said his back felt better Tuesday night than in the two previous outings, blaming the high pitch count on Rockies hitters, who fouled off 27 pitches.

His velocity was down about two miles an hour on the radar gun, but his curveball was again biting. Whatever physical problem he has seems to bother him the least while pitching. Running the bases is a different story, and that's what he had to do in the second inning when he singled and eventually scored from second base on Kenny Lofton's triple.

"Actually, [the back] felt pretty good tonight," said Penny. "The pitch count was just too high. I kept throwing strikes; they kept fouling them off. But I'm not going to throw it over the middle of the plate or they'll crush it."

Pitching coach Rick Honeycutt said he was satisfied that the injury was not compromising Penny's pitching.

"It's not really affecting his delivery," he said. "Our biggest concern was, 'Would he change his mechanics or arm angle?' And he hasn't done that. It seems to be worse early on in the game, but once he moves around and loosens up, he's okay. Between innings, they keep the heat pack on him so it doesn't spasm, like it did in San Francisco [two starts back]."

This is Penny's best start to a season since he began 7-1 for Florida in 2001, and Tuesday night he was given an early lead with which to work. The offense scored two runs in the first inning off Jason Jennings on an RBI triple by J.D. Drew and a double by Willy Aybar. Two more runs scored in the second inning on Lofton's triple, one of his three hits, raising his average to .304.

An offense that leads the league in runs continued to produce relentlessly. Nomar Garciaparra had an RBI double and Jeff Kent added a sacrifice fly in the seventh inning, while Russell Martin had an RBI double and Rafael Furcal a sacrifice fly in the eighth. Seven Dodgers drove in runs.

Penny's early departure, however, pressed three relievers into duty. Tim Hamulack allowed a solo homer to Garrett Atkins in the sixth, but Danys Baez threw two scoreless innings with three strikeouts and Takashi Saito pitched a scoreless ninth.

The victory ran Penny's career mark against the Rockies to 7-2 and his Dodger Stadium record to 10-5. The victory was the 14th in the last 17 games for the streaking Dodgers, who remained one-half game behind the first-place Diamondbacks.

"There are certain guys you don't have much success against," Colorado manager Clint Hurdle said of Penny, who beat the Rockies at Coors Field six days earlier. "I wouldn't say we're embarrassed that he's been tough on us, because he's a good pitcher. But we had an opportunity to do something early, weren't able to do it, and basically, we were shut down after that."

Penny fell an inning short of qualifying for another quality start by a rotation of starters that have yet to throw a complete game, but they're pitching pretty well for as long as they last. Dodgers starters are 9-2 during the 17-game stretch, and their ERA on the season is 3.52.

In five games on this homestand, they have outscored opponents, 45-8. Five of the eight position starters (Lofton, Garciaparra, Aybar, Andre Ethier and Martin) are batting above .300 and Drew is at .295.

"We knew Kent and Furcal would start hitting," said Penny. "Now we're not making stupid mistakes on defense and the pitchers aren't making stupid pitches. Those are the keys."

Penny gets six more days before his next start because of Thursday's travel day.