Wilin Rosario has been a bright spot in a lost season for the Colorado Rockies.

The rookie catcher hit his team-leading 24th home run Wednesday night, but it wasn't enough to overcome a rough first inning against San Francisco.

Tim Lincecum pitched effectively for six innings to extend his road winning streak to a career-best five straight, Brandon Crawford doubled twice and drove in two runs, and the Giants beat the Rockies 8-3.

It was Colorado's eighth loss in its last 10 games, increasing the chance this squad will finish with the worst single-season record in franchise history. The Rockies (57-85) need to win half of their last 20 games to avoid setting the dubious mark.

If Rosario keeps hitting Colorado has a chance to finish strong. His blast in the third tied Troy Tulowitzki for second-most homers by a Rockies rookie in team history.

"I'm strong, but I don't go to the plate thinking I can hit it far," Rosario said. "If you make a mistake, I'll take it, but I don't look to hit a home run."

Rosario's emergence has given the Rockies something to build on.

"Compile me a list of guys who catch who is sitting on the potential for 30-plus and 100-plus because that's what this kid's offensive ceiling is capable of," manager Jim Tracy said.

Rosario finished with two hits and one homer shy of Todd Helton's rookie mark set in 1998. He nearly tied the record with a long drive to center in the seventh but Gregor Blanco tracked it down at the wall.

"I don't think I hit that ball very good," he said. "I didn't think it was gone."

It wouldn't have been enough to overcome Colorado's slow start against the NL West-leading Giants. Starter Jeff Francis (5-5) couldn't recover from a tough first inning and took the loss, allowing five runs on seven hits in three innings. He struck out five and walked none.

"The first inning got us tonight," Tracy said. "The opposition had five runs and six hits before we put a bat in our hands."

Blanco tripled off Francis to start the game and scored when Marco Scutaro followed with a single. Buster Posey and Joaquin Arias each singled around Hunter Pence's fielder's choice to account for another run and Hector Sanchez hit an RBI single ahead of Crawford's two-out, two-run double that rolled to the right field wall.

"The (pitch) to Sanchez was a half-decent pitch," Francis said. "He had his back foot off the ground when he hit it. But the ball to Crawford was just a hanging curveball and he put a good swing on it."

Colorado pulled to 5-2 behind Rosario's RBI single in the first and his solo homer in the third. Rosario drove Lincecum's 83 mph changeup deep into the left field bleachers.

Lincecum (9-14), who allowed three runs on six hits, has figured prominently in Giants' recent road success, going 5-0 with a 2.61 ERA in his last five road starts. The two-time NL Cy Young award winner had struggled on the road earlier, going 1-6 with a 9.00 ERA through his first 10 starts away from home.

He finished with eight strikeouts and four walks.

"There's erratic command with his fastball," Tracy said. "The strikes he threw tonight he threw with his slider and got some changeups over the plate. From what I've seen in the past, I've seen Timmy Lincecum be more consistent with his fastball command. That's not the case right now, and I'm not basing that on what I saw tonight.

Down 6-2 in the sixth after Crawford doubled for the second time and scored on Scutaro's second single, the Rockies added a run in their half of the sixth on Charlie Blackmon's pinch-hit RBI double.

But the Giants added a pair of runs in the ninth on a run-scoring triple by Hunter Pence and Arias' sacrifice fly.

NOTES: A second MRI on Rockies C Ramon Hernandez revealed a torn tendon in his left hamstring. He will have season-ending surgery next week. ... The Rockies also have Thursday off, their final off day of the season. ... Penny Chenery, a resident of nearby Boulder who owned and bred 1973 Triple Crown winner Secretariat, attended the game.