OAKLAND, Calif. -- Mark Ellis was surprised to learn his hitting streak was up to a career-high 11 games.
The veteran second baseman has something else on his mind.
Ellis scored the tiebreaking run on Rajai Davis' triple in the seventh inning and Andrew Bailey struck out David Ortiz with the tying run on second to end the game, preserving the Oakland Athletics' 4-3 victory over the Boston Red Sox on Saturday night.
Oakland improved to 6-2 on its nine-game homestand. Still clinging to faint playoff hopes, the A's trailed AL West-leading Texas by 7½ games before Saturday's action.
"A lot of guys in this clubhouse have never been through this before, and to still have a chance and to have meaningful games in September is huge," Ellis said. "It's old hat for a lot of teams but for some guys around here it's not."
Ellis said he doesn't care about his hitting streak.
"I don't think I'm going to break Joe DiMaggio's record," he said.
The victory capped a big day for A's manager Bob Geren, who is set to return to Oakland's dugout next season. The team announced before the game it had exercised its option on Geren's contract for the 2011 season, ensuring him of a fifth year in charge of the club.
"At the end of the day it seemed pretty obvious to all of us," general manager Billy Beane said. "For us it's critical that we have a manager that's not only a teacher but has the patience to get through some of the growing pains a young player's going to have. Bob and the rest of the staff have certainly done that."
Oakland scored three times in the seventh and once in the eighth, erasing a 2-0 deficit and clinching its first season-series win over the Red Sox since 2006. Ellis hit a tying RBI single before coming around on Davis' hit.
John Lackey (12-10) pitched seven innings for Boston, yielding three runs and six hits. The right-hander fell to 17-5 with a 2.90 ERA in 31 career starts against Oakland.
Lackey was working on a two-hit shutout before Oakland rallied in the seventh.
"I made a couple of mistakes in the seventh; other than that I was pretty much in control," Lackey said. "In our situation you can't make too many mistakes. In the first half of the season we were hitting the ball all over the place. Right now we need to pitch well and win games."
Adrian Beltre doubled in Victor Martinez with two out in the ninth to get Boston within one but pinch-hitter Ortiz looked at a called third strike, giving Bailey his 23rd save in 26 opportunities this season.
Martinez, Beltre and Darnell McDonald had two hits apiece for Boston, which has lost six of eight and is struggling to stay in the playoff picture. The Red Sox were nine games back of the AL East-leading Yankees and 7½ back in the wild-card race entering play Saturday.
"We had a good game going but we left some runs out there early and it caught up with us late," Boston manager Terry Francona said. "The pitch to Davis was a fastball that caught too much of the plate. That was obviously the key at-bat."
Daric Barton started the Oakland seventh with a double and scored on Jack Cust's one-out single. Cust took second when left fielder Bill Hall briefly bobbled the ball and came home on Ellis' tying hit to center.
After Jeremy Hermida struck out, Davis tripled to center to make it 3-2.
Lackey, who beat the A's earlier this season despite allowing four earned runs and a season-high 12 hits, struck out six and walked none. The Red Sox have scored seven runs total in his last three games, all losses.
"Lackey's thrown a lot of good games in this ballpark when he was with Anaheim," Ellis said. "It looked like he was going to have the same outcome early in the game but we put some good at-bats together and we were able to string some together late."
Brett Anderson (5-6) scattered eight hits over seven innings for Oakland. He struck out five and walked three.
Marco Scutaro homered for Boston, which has lost eight of its last 12 road games.
Scutaro, making a rare second straight start at second base, has reached base in 20 of his last 24 games. The home run was his fourth in September and 11th overall.
Oakland 3B Kevin Kouzmanoff (back spasms) did not play and likely won't return to the A's lineup until next week when the team is on the road. ... Oakland RHP Joey Devine threw 20 pitches in a simulated inning and reported no pain. ... The A's have stolen 135 bases this season, their most since swiping 143 in 1992. Coco Crisp has stolen 20 consecutive bases, the longest streak by an Oakland player since Stan Javier had 28 straight.