Betancourt hit one of his mistakes, a 1-0 fastball. Kenji Johjima hit the other, a 1-0 slider for a two-run home run in the second inning. It was part of a three-run Mariners rally as they responded to the A's three-run rally in the top of the inning.
"He threw well,'' Mark Kotsay said of Gaudin. "We just didn't give him enough runs.''
Oakland had jumped on Seattle starter Horacio Ramirez (6-3) in the second. Mike Piazza started it with a leadoff single to right. With one out, Dan Johnson drew a walk. Marco Scutaro then loaded the bases with a single to center.
Donnie Murphy laced a 3-1 pitch for a bases-clearing double to center. Scutaro raced around from first and didn't even draw a throw to the plate.
However, Adrian Beltre doubled off Gaudin to begin the Mariners' equalizing rally. Raul Ibanez flied out to center, but Beltre tagged and reached third on a close play. After Richie Sexson walked, Ben Broussard hit a sacrifice fly to left, scoring Beltre. Johjima followed with his two-run home run, his 11th.
Gaudin had similar trouble in his previous start, on Monday against the Angels. He was given a 9-2 lead but couldn't get out of the fourth inning, allowing three runs.
But this was a much better performance. He had walked 16 batters over his previous three starts, but he issued just one Saturday. Gaudin threw only 88 pitches and finished the game by retiring 16 of the final 17 batters. The only blemish was Betancourt's home run.
"Chad pitched extremely well today," A's manager Bob Geren said. "He just made a couple of mistakes over the middle of the plate, and they capitalized on both of them. Other than that, he actually pitched great. He had a real low pitch count and was aggressive.''
The A's had a couple breakout opportunities. One came in the fifth after Ramirez walked the bases loaded with two outs. Kotsay followed with a two-hop shot just to the left of second baseman Jose Lopez, who managed to snag it and throw out Kotsay.
"It is a game of inches,'' Geren said. "Johjima's ball hit the top of the wall. If that's two inches shorter, it's a double. Kotsay hit a rocket to second. If that's six inches to the right, that's through for two runs.''
The A's also put a couple runners on in the eighth with two outs, but Seattle closer J.J. Putz came in to strike out pinch-hitter Jack Cust. Putz worked the ninth by striking out Shannon Stewart and Kotsay, walking Nick Swisher and striking out Piazza to pick up his 30th save.
"Obviously, I didn't have a good day. I left five guys on,'' Kotsay said. "With the bases loaded there, I hit it hard but right at the second baseman. I squared it up, but just not a positive result. That's kind of the story of the year for me.''
Kotsay added that Putz's ball "just explodes. He threw me an 0-1 split at 90 mph. That's why his ERA is less than one [0.93] and has blown one save in 31 chances.''
The A's had the misfortune of facing Ramirez at home. The left-hander is 6-0 with a 2.63 ERA at Safeco Field, while he is 0-3 with a 13.72 ERA on the road. He is 2-0 with a 6.48 ERA against the A's.
The A's, down 1-2 in the four-game series, close it out Sunday with lefty Lenny DiNardo facing southpaw Jarrod Washburn.