OAKLAND, Calif. -- The Red Sox are limping back to Boston after watching the Oakland Athletics finish off a three-game sweep with a 3-2 win Wednesday.

In a seven-game road trip against two teams -- the A’s and Seattle Mariners -- with losing records, the Sox went 2-5.

The offense didn’t produce much outside of David Ortiz’s 400th career home run, a game-tying shot in the fourth inning. Yet the Red Sox still managed to take a 2-1 lead with an unearned run in the sixth.

Starter Aaron Cook couldn’t hold that lead. He was tagged for runs in the sixth and seventh as the Sox were left wondering what went wrong on the dreadful trip west.

Boston scored only 14 runs in the seven games and scored more than two runs only once.

As recently as Monday, the Red Sox were a win away from moving into second place in the American League East. Now they need the Toronto Blue Jays to lose to the Kansas City Royals on Wednesday night to avoid falling into a tie for last place. They haven’t been in the cellar since June 19.

With the first-place New York Yankees coming to town Friday for a three-day, four-game series, the Red Sox need to put it together quickly.

Cook battled trouble all day, giving up nine hits in six-plus innings.

The A’s took the lead in the second inning by repeating a familiar refrain when Brandon Moss hit a solo home run.

It was Moss’ second home run of the series and the fourth long ball hit by a former Red Sox player in the series. Josh Reddick and Moss both homered Monday and Coco Crisp homered Tuesday. Nine of the 12 A's runs in the series were driven in by the trio of former Sox.

Ortiz tied the game in the fourth when he became the 49th player in major league history to reach 400 career home runs.

Boston took a 2-1 lead in the sixth when Ortiz walked with two outs, Jarrod Saltalamacchia reached on an error and Adrian Gonzalez singled home Ortiz.

The A’s tied it in the bottom of the sixth when Moss and Brandon Inge both collected doubles. They took the lead in the seventh when Crisp tripled and scored on Jemile Weeks’ single off reliever Andrew Miller.

The final 10 Red Sox batters were retired in order and A’s rookie All-Star closer Ryan Cook needed only seven pitches to fire a perfect ninth inning.