SAN FRANCISCO — Barry Zito's maddening season is proving more impossible to gauge than Dow Jones.

One start after tossing eight shutout innings, the Giants' $126 million left-hander took another sharp turn downward last night, losing control in a five-run third inning as the Los Angeles Dodgers took a 6-2 victory on a chilly night at AT&T Park.

Manny Ramirez wasn't a factor in his first official turn as an antihero in San Francisco. Instead, a more familiar villain — Jeff Kent — contributed the three-run double that sent Zito to a 14th loss for the first time in his career.

The Dodgers improved to 17-5 over their last 22 games in San Francisco, a run of dominance that spans three seasons.

An abysmal first half virtually assured that Zito (6-14) would break his personal mark for losses in a season. He had lost 13 games with the A's in 2005 and matched that total last year.

But it was the manner in which he stepped back that was most disheartening. He still hasn't won consecutive starts since Sept. 24-30 of last season.

There was every reason to believe that Zito would have a solid outing against the Dodgers. He was coming off his best start of the season, in which he threw eight shutout innings while outdueling San Diego's Jake Peavy in a 2-0 victory at Petco Park.

And Zito's stuff was even more impressive in his last look against the Dodgers on July 5, when he struck out 10 in seven innings of a 5-2 win. Before that effort, Zito had been 0-8 in nine starts at AT&T Park.

But Zito didn't have swing-and-miss stuff.

He retired six of the first seven hitters, but several of the outs came on hard-hit balls. At least he wasn't falling behind hitters, though.

He began to slip in the third. The Dodgers batted around and Zito fell behind seven of the nine hitters he faced. He went to 2-0 counts six times in the inning.

The results, then, weren't surprising. Danny Ardoin smacked a leadoff home run on a full-count sinker that he appeared to be geared up to hit. Two singles and a walk loaded the bases for Kent, who appeared similarly primed for a 2-2 curveball that Zito left at his belt buckle.

Kent's shot rolled to the wall in left-center, clearing the bases.

After Ramirez and Casey Blake flied out, Zito ran into more trouble. He walked .164-hitting Andruw Jones on five pitches and served up a double to Angel Berroa that scored Kent. Zito was rescued from the inning by a taut relay from Aaron Rowand to Ivan Ochoa to the plate that cut down Jones.

Zito threw a whopping 41 pitches in the third inning, just 20 for strikes. He didn't allow a run in the next two innings, and got his only strikeout — nine fewer than his previous start against the Dodgers — when Kent looked at a pitch in the fifth.

In his first taste of the Giant-Dodger rivalry, Ramirez was derided with chants from the left field bleachers and booed upon introductions. But it was rather tame compared to the usual boos reserved for Kent, and it didn't approach the treatment that Barry Bonds used to receive whenever he would suit up at Dodger Stadium.

Ramirez had a quiet night to match his reception. He was 0-for-5, raced down the line to catch Fred Lewis' drive in the sixth inning and handled John Bowker's liner in the first.

Ramirez even hustled down the line after Rich Aurilia misplayed his ground ball for an error in the seventh.

The most striking part of Ramirez's appearance, other than his long dreadlocks, was a blue helmet shellacked in pine tar that appeared to have gone through the wars — a nifty trick, considering he had been a Dodger for a week.