Kottaras hit a leadoff homer in the 10th inning and the A's moved within four games of the division lead by beating the first-place Texas Rangers 3-2 Tuesday night.
"To do that and help the team in that manner was huge for me," Kottaras said. "I went up there looking for a fastball and he threw one that I could handle."
Before that, Oakland hitters were having a miserable time against the Texas bullpen. The A's managed only one hit and struck out nine times in five innings against Michael Kirkman, Koji Uehara and Alexi Ogando.
Kottaras hit a 3-2 fastball from Lowe (0-2) into the first row of the upper deck in right field. The catcher has six home runs for the A's since he was acquired July 29 from Milwaukee.
The A's remained two games ahead of the Los Angeles Angels for the second AL wild-card spot. The Angels beat Seattle 5-4.
"Each and every win has a little bit more magnitude to it, especially against a team that's above you," Oakland manager Bob Melvin said. "This team's responded like this many, many times this year. It doesn't surprise me."
Lowe hadn't pitched in a week and has given up six runs in his last 1 1/3 innings. Nathan and Adams had pitched the past two days.
"Some of those other guys in the bullpen have to come in and get outs," Texas manager Ron Washington said. "It can't always be Joe Nathan or Mike Adams."
Texas' magic number remained at five for clinching its third straight division crown.
Feldman was removed after allowing a leadoff single to Kottaras in the fifth. The right-hander gave up two runs and four hits in four-plus innings before being relieved by Kirkman.
"I wanted to go as long as I could," said Feldman, who threw 75 pitches. "I would have loved to have thrown 100 pitches."
The A's lost the opener of the four-game series 5-4 Monday night. The teams play five more times over the final eight games of the season.
Oakland has played five consecutive one-run games, winning two. The A's are 3-5 on a 10-game road trip against Detroit, the New York Yankees and the Rangers.
"It's an exciting feeling to be in this position," Kottaras said. "All we can do is control how we play. We've had a bunch of tough losses, but we keep pushing."
Chris Carter hit a solo homer for the A's with two outs in the fourth to tie the score at 2. He came into the game in a 6-for-45 funk with 27 strikeouts over his last 14 games.
Oakland starter Tommy Milone gave up three straight singles to start the game before retiring 15 of his next 16 batters. The young lefty yielded two unearned runs and six hits over six innings.
"Any win is big for us and kind of gives us momentum going into the last two games of the series," Milone said.
Moss, who played his 21st game in the outfield this season, started in right for a slumping Josh Reddick -- mired in an 0-for-28 slump.
Reddick came in as a pinch-hitter and lined out to end the eighth.
Moss made up for his misplay with a running catch of Andrus' deep fly on the warning track with the bases loaded to end the seventh.
Daric Barton, making his second start since being recalled from Triple-A Sacramento on Sept. 10, had an RBI double in the second to cut Oakland's deficit to 2-1.
Oakland CF Coco Crisp came in as a pinch-runner in the eighth and stole second. He was not in the starting lineup for the seventh game in a row because of an eye infection. ... Andrus came into the game in a 4-for-32 slump. ... The A's struck out 15 times and have 1,322 for the season, two short of the AL record set in 2007 by Tampa Bay. ... Former Dallas Cowboys quarterback Roger Staubach was in a front-row seat near the Texas dugout.