PHOENIX - The San Francisco Giants were cruising at the start of June, their lead up to nearly 10 games.

The past two weeks have been frustrating, the lead dwindling and the answers hard to come by.

Tim Lincecum laboured through six innings, and the Giants repeatedly let Josh Collmenter off the hook in losing their sixth straight game, 4-1 to the Arizona Diamondbacks on Friday night.

"It's been that way here through this tough streak," Giants manager Bruce Bochy said. "We are missing the big hit, kind of keep the line moving. We had some great at-bats, stretched him (Collmenter) out, but he dodged some bullets there."

The Giants still lead the NL West, but have lost nine of 10 to see a lead that was once 9 1-2 games down to less than four.

The last-place Diamondbacks extended San Francisco's misery behind a gritty effort by Collmenter (5-4) and by knocking around Lincecum (5-5).

Collmenter fought through five innings to win for the first time in four starts, and Arizona's bullpen picked it up from there.

Three pitchers worked scoreless innings, and Addison Reed had a perfect ninth to close out his 17th save and Arizona's third win in 10 games.

Hill had run-scoring hits in the fourth and fifth innings against Lincecum, and Goldschmidt had a single and double to raise his average to .577 against the two-time Cy Young Award winner.

"You don't want to take it lightly because baseball can turn at any moment," said Hill, who is 11 for 19 against Lincecum. "He is a great pitcher and had a great career, and you don't want to make it sound like it's easy. He's a great pitcher and it's not easy."

Collmenter had lost two straight starts, allowing six runs in six innings against the Los Angeles Dodgers his last time out.

The right-hander laboured through his night, needing 31 pitches to get through the first. Pablo Sandoval had a run-scoring triple in the inning, chugging his way around the bases after centre fielder Ender Inciarte just missed a diving catch in the gap.

Collmenter continued to run up his pitch count, yet found ways to wriggle out of jams. He walked two in the fifth inning and got out of that by striking out Sandoval and getting Michael Morse to fly out to deep centre.

Collmenter allowed a run and four hits, struck out four and walked four while throwing a season-high 109 pitches.

"I just continued to battle," Collmenter said. "I don't think I've ever had a clean, crisp outing against these guys for whatever reason. But I felt as good as I have in the last few starts and was able to make some good pitches."

Lincecum was solid in his previous two starts, allowing five combined runs after giving up eight against Cincinnati on June 3.

Like Collmenter, he struggled. Unlike Collmenter, he didn't always get out of it.

Arizona scored two runs off the right-hander in the fourth inning, on Hill's single and a double by Martin Prado. Arizona added a run in the fifth on a run-scoring triple by Chris Owings, who was thrown out at the plate while trying for an inside-the-park homer.

Hill made it 4-1 with a sacrifice fly that scored Goldschmidt, who improved to 15 for 26 against Lincecum with his second hit of the night, a double off the wall in left-centre.

Lincecum allowed four runs and seven hits in six innings.

"I left too many pitches over the plate, and you saw what they did with them," Lincecum said.

NOTES: The Diamondbacks signed first-round draft pick Touki Toussaint. Arizona took the right-hander from Coral Springs (Fla.) Christian Academy with the 16th pick in this year's draft. ... Giants OF Angel Pagan missed his fourth straight game with lower back pain, but Bochy said he could be back in the lineup Saturday night. ... Arizona RHP Brandon McCarthy will pitch in the middle game of the series against Giants RHP Ryan Vogelsong.