OAKLAND, Calif. (AP) -- Josh Reddick provided a fitting ending to a promising first half of the season for the Oakland Athletics.

Reddick capped a remarkable first half by hitting a game-ending RBI double in the 13th inning to send the A's into the All-Star break with a .500 record by beating the Seattle Mariners on Sunday.

''It feels great,'' Reddick said. ''This team has struggled right around the .500 mark and we seem to just fall off every time we get close. For us to go in halfway through this thing at .500 is huge.''

Reddick has been a big reason why. Reddick came over last December from Boston in a little-noticed acquisition but has been a big part of Oakland's surprising success so far with 20 home runs and other clutch hits like his game-winner Sunday.

Jemile Weeks led off the 13th with a single off Oliver Perez (0-2) and then raced around the bases to score on Reddick's drive to left-center field that gave the A's their major league-leading eighth walk-off win of the season and second this series.

''He's come up big in big situations,'' Weeks said. ''He's provided power, maybe even more than people expected. He's definitely doing his job and then some.''

Jordan Norberto (2-1) pitched a scoreless 13th for the win. He worked around a two-out double to Michael Saunders on a fly ball to right center that Coco Crisp and Brandon Moss lost in the sun and a flock of seagulls that hovered over the field in the extra innings.

''You could see them,'' manager Bob Melvin said. ''It was like the movie 'The Birds.'''

Oakland's Bartolo Colon was sharp in his second start back from a strained right oblique injury, allowing one run and seven hits in 8 2-3 innings. He struck out five, walked none and was extremely efficient, throwing just 93 pitches before being replaced after Justin Smoak's double put runners on second and third.

All-Star Ryan Cook struck out Miguel Olivo to end the threat and make sure Colon's strong outing didn't go to waste. It's that type of performance that could make Colon a potential trade target for a contender needing a proven starter before the July 31 deadline.

The A's (43-43) are much closer to contention than almost anyone thought they would be at the break, trailing Baltimore by just 2 1/2 games for the second AL wild-card spot. Oakland reached the All-Star break without a losing record for the first time since 2008.

Felix Hernandez allowed an RBI infield single to Yoenis Cespedes in the first inning and nothing else in 7 2-3 innings. Hernandez, who is headed to the All-Star game in Kansas City, has once again been one of the few bright spots for the Mariners (36-51).

Seattle has lost nine of 14 and goes into the break with a losing record for a third straight season as the hitters once again struggled to generate any offense.

''That's the No. 1 area where we've got to get a lot better and we have to damn sure be more consistent,'' manager Eric Wedge said. ''They have to be ready to come back and be a better ballclub in the second half and be a more balanced ballclub.''

Colon allowed a leadoff single to Dustin Ackley to open the game and then retired the next 17 batters he faced, throwing 16 straight strikes at one point. But with two outs in the sixth, Ackley singled again to start a rally. Ichiro Suzuki, who broke a career-worst 0-for-23 slump on Saturday night, then blooped a ball that landed just fair down the left-field line for a single.

Saunders lined the next pitch to right field for an RBI single that tied the game at 1. But that is all the Mariners got, leaving Hernandez with a no-decision

''I believe in this team,'' Hernandez said. ''I believe in these guys. We're going to be better. It cannot happen all the time so we're going to be better.''

Cespedes left the game after the third inning with a sprained left thumb he injured on a stolen base in the first inning. Melvin hopes Cespedes will be ready when the second half begins Friday in Minnesota.

NOTES: The last time the A's played a game of at least 13 innings without issuing a walk was Aug. 6, 1927, against the St. Louis Browns. ... Seattle reliever Charlie Furbish threw a wild pitch while issuing an intentional walk to Josh Reddick in the 10th. ... Nine former members of the Oakland Oaks of the Pacific Coast League were on hand for the turn back the clock game with the Mariners wearing uniforms of the 1955 Seattle Rainiers and the A's dressed as the Oaks. ... Athletics LHP Brett Anderson (elbow) threw a bullpen session before the game and will next throw a simulated game in Arizona on Wednesday. ... Oakland OF Colin Cowgill (sprained left ankle) ran the bases before the game and is set to begin a rehab assignment at Class-A Stockton on Monday.