CHICAGO — Billy Butler's ninth-inning drive cleared the right-field wall and Avisail Garcia's glove — barely.
"I saw him catch it, and when I saw the bullpen's reaction, it was a pretty cool feeling," Butler said. "When I saw their hands go up, I realized it had gone over the fence."
Chicago led 2-1 but Robertson (6-4) blew a save for the seventh time in 36 chances. Brett Lawrie doubled, Danny Valencia singled, and Butler hit his 13th homer.
Garcia jumped at the wall and appeared to snag Butler's drive, but the ball fell out of his glove and into Oakland's bullpen as Garcia hit the fence.
"We've caught enough bad breaks this year," Butler said. "To have one go our way, I think it was deserving for all the tight games we've lost throughout the year."
Butler also homered in Wednesday's 9-4 loss. In Monday's series opener, Robertson wasted a 7-3 lead — two of the four runs were unearned — before Chicago won 8-7 in 14 innings.
"He's tough," Oakland manager Bob Melvin said. "Any time you can beat a closer like that, you have to feel good about it."
Even if Garcia had caught Butler's drive, Lawrie would have scored from third with the tying run.
"I'm just furious with myself," Robertson said.
Sean Doolittle (1-0) pitched a scoreless eighth and ninth. Rookie Sean Nolin allowed two runs and five hits in five innings in his third start since being recalled from Triple-A Nashville on Sept. 4.
"We just didn't give him much run support," Melvin said. "He's got a good mix of pitches."
White Sox starter Jose Quintana pitched crisp four-hit ball through seven innings and Mike Olt homered for the second straight day.
Quintana allowed one run, struck out six and walked one. In his last 20 innings, the left-hander has allowed two earned runs and 15 hits, while fanning 16.
"We know he's a good pitcher," White Sox manager Robin Ventura said. "You don't question that at all. Whether he's going to get some run support, that's the other question."
Athletics: INF Danny Valencia (trapezius muscle stiffness) started at third base after missing two games. ... OF Billy Burns (right hamstring) participated in pregame workouts for a fourth straight game. Melvin said Burns was no longer feeling any discomfort.
White Sox: OF Trayce Thompson (hyperextended left elbow) missed his third straight game. ... OF J.B. Shuck left in the seventh with left hamstring tightness.
Athletics: LHP Felix Doubront (3-2, 4.99 ERA) faces Astros RHP Mike Fiers (7-10, 3.67 ERA ) as the A's open a three-games series in Houston.
White Sox: Ace lefty Chris Sale (12-9, 3.55 ERA) will try to rebound against Indians RHP Cody Anderson (4-3, 3.68 ERA) on Friday night in the opener of a three-game set at Cleveland. Sale gave up six runs and nine hits in three innings against Minnesota last Sunday, his shortest outing this season.