OAKLAND, Calif. (AP) -- Olmedo Saenz is becoming all too familiar to the San Francisco Giants.

Saenz again battered Giants pitching with a solo home run among his three hits and Miguel Tejada added a three-run homer as the Oakland Athletics beat cross-bay rival San Francisco 5-4 Friday night to open the interleague series.

"I just have a good feeling right now. Maybe something is going on," said Saenz, remembered by the Giants for hitting a game-winning three-run homer off closer Robb Nen in the ninth inning of an 11-9 Oakland victory July 15.

"I think I'm just being more patient now and getting good pitches to hit," the A's designated hitter added.

Saenz improved to 9-for-22 lifetime (.409) against the Giants. He is a career .345 hitter in interleague play.

"Maybe we're pitching him wrong. We don't see him that often," San Francisco manager Dusty Baker said.

There were plenty of people around to see Saenz's latest performance against the Giants. A sellout crowd of 51,678 turned out for the game, the second-largest baseball crowd ever at the Oakland Coliseum. The A's drew a record 53,948 on opening night against Detroit on April 3.

Saenz said the A's, who have struggled at times with attendance, fed off the crowd's energy even though its loyalties were divided between the two local teams.

"This is a lot better than playing in front of 6,000 people," Saenz said. "What was really nice is we got a win in front of this many people."

Added Jason Isringhausen, who pitched a perfect ninth for his 12th save: "We had people booing and people cheering. Sure, it was loud but I liked the noise. I don't care if I get booed or cheered. I just like the noise."

The A's won for the eighth time in 15 meetings with the Giants since interleague play began in 1997.

Mark Mulder (3-2) went five-plus innings and allowed three runs on seven hits. Isringhausen retired Barry Bonds on a grounder to end it.

"It was an entertaining game. I just wish we had won instead," Baker said. "Russ (Ortiz) pitched well. He just gave up a couple bad pitches, one to Tejada and the other to Saenz."

The Giants got help from their designated hitter, Russ Davis, who had three hits, including a two-run homer in the sixth. Jeff Kent also homered for San Francisco.

Ortiz (3-6), losing for the fourth time in five decisions, allowed five runs on eight hits in 6 2/3 innings.

"I have to continue to get my form back," Ortiz said. "Really, all I did was give up two big pitches and that hurt us. I don't know what it is. Maybe it is my concentration on those pitches. I need to put the ball where I want it to be."

Mulder kept the Giants in check until the sixth when Kent worked the count full before connecting for his 14th homer. Ellis Burks singled and went to second on Mulder's throwing error and Davis then homered, pulling the Giants to 4-3.

J.T. Snow reached second on shortstop Tejada's throwing error and T.J. Mathews relieved Mulder, inducing three fly outs to get out of the inning.

The A's added a run in the bottom of the sixth when Saenz had a leadoff double and scored on Eric Chavez's two-out single.

San Francisco had runners on the corners with none out in the seventh, but reliever Doug Jones came on to retire Kent on a shallow fly to right and then picked Bonds off first before Burks grounded out.

Saenz and Matt Stairs singled to start the second and Tejada followed with a drive into the left-field bleachers for his eighth home run, putting Oakland up 3-0. Saenz made it 4-0 with a one-out home run in the third.

Game notes
Saenz and Davis, the two DHs, were a combined 6-for-8. ... Bonds fell to 0-8 lifetime against Isringhausen. ... The Giants have homered in 41 of their 51 games. ... The Giants have started 6-4 on a 24-game stretch in which they'll play within California. San Francisco will play 18 times at Pac Bell Park, two more in Oakland and three at Anaheim. ... The teams will play in throwback uniforms Saturday with the A's wearing replica jerseys from the 1911 Philadelphia A's and the Giants outfitted in the attire of the 1911 New York Giants. In another throwback, Oakland manager Art Howe will wear a suit to present the A's starting lineup just as Connie Mack did when he managed the A's from 1901-50. Mack was named manager on the A's all-century team announced earlier this week. ... Felipe Crespo's RBI single in the eighth was his seventh hit in 15 pinch-hit at bats.