PHOENIX (AP) -- Brandon Webb looked like an All-Star -- at the plate.
On a night he struggled with his command, Arizona's light-hitting ace had a two-run double and improved to 5-0 as the Arizona Diamondbacks defeated San Francisco 5-4 on Tuesday night.
Webb's teammates often razz him about his feeble hitting. But Webb produced the biggest hit against San Francisco's Barry Zito (0-5), whom he beat for the second time in six days.
"I let everybody know whenever I came in the dugout today," said Webb, who raised his career average to .108. "They know I hit the ball pretty hard. They know what I can do."
Webb is off to the best start of his career, and his five victories match the total of the Giants' rotation. He allowed three runs and nine hits in six innings. He walked two and struck out a season-high seven.
Webb spotted the Giants a 3-0 lead. But he hit a two-run double in the fourth -- his second two-run hit off Zito this season -- to give the Diamondbacks a 4-3 lead.
Thanks in no small part to Webb, Arizona is 15-5 and leads the NL West by six games, a bigger margin than it had at any point en route to the division title last year.
"With 'Webby' on the mound, you expect to win all the time," Arizona manager Bob Melvin said.
The last time Webb faced the Giants, on April 16, he allowed only three hits in eight innings. It took San Francisco four batters to match that total Tuesday night.
The Giants made it 3-0 in the second on RBI singles by Lewis and Winn.
"It was a battle all day, pretty much," Webb said. "It was one of those days where my arm didn't feel real live. But I ended up battling through it."
In Zito's first four starts, his biggest lead had been one run, and it lasted less than an inning.
This time, his lead lasted less than three innings. Arizona cut it to 3-2 in the second on a two-run single by Chris Snyder, his sixth hit in 10 at-bats against Zito.
In the fourth, Mark Reynolds led off with a single and Justin Upton walked. Zito got the next two batters to bring up Webb, who hit Zito's first pitch into the gap in left-center field to give the Diamondbacks a 4-3 lead.
Webb said he was looking for a fastball "where I could hit it.
"It ended up being a fastball, and I was pretty much swinging no matter what," he said. "I ended up getting a pretty good piece of wood on it and getting two RBIs, which was huge."
Webb's only other hit and RBIs of the season had come against Zito last week.
Zito said he had tried to throw a fastball away and left it over the middle.
"We knew he was going to be hacking there," Zito said. "He just wants to put the ball in play, and I served it right up."
Webb scored on Eric Byrnes' single to put the Diamondbacks ahead 5-3. Webb thought he would score easily, but as he chugged toward the plate he saw second baseman Orlando Hudson frantically waving for him to slide.
It was too late, and Webb danced around catcher Bengie Molina's tag.
"I'm thinking I'm out if I slide," Webb said. "Or I hurt myself."
Zito gave up five runs and six hits in 3 2/3 innings, his shortest outing. He walked three and struck out two.
"I take all the blame here," Zito said. "Our guys came out, did what they had to do against a good pitcher and I was unable to hold them down."
Manager Bruce Bochy had a brief evaluation of Zito's night.
"It was not a good outing for him, and I'm going to leave it at that," Bochy said.
San Francisco cut the lead to 5-4 in the eighth on Lewis' double off Tony Pena. Pena struck out Winn looking on fastball over the inside corner to strand the potential tying run at third.
Brandon Lyon pitched the ninth for his fifth save in seven chances.
Fred Lewis had three hits and two RBIs for San Francisco.
Bochy was ejected in the sixth by home plate umpire Andy Fletcher. Bochy argued that Arizona 3B Reynolds touched a ball that was ruled foul -- and television replays appeared to support Bochy. ... San Francisco SS Emmanuel Burriss singled up the middle in the eighth for his first big league hit. ... Zito is 66-63 since winning the AL Cy Young Award in 2002. ... Arizona 3B Chad Tracy, who is returning from knee surgery, ran the bases before the game. Tracy also took grounders at first base, where he's likely to see action in the late innings. Tracy will start a rehabilitation stint in extended spring training on Wednesday, with his first game action coming on Friday, Melvin said.