SEATTLE -- The A’s entered an important four-game series against the Mariners with a chance to reaffirm themselves as the main competition to the Astros for first place in the American League West. Instead, they left T-Mobile Park by opening the door for a three-team division race.

A feel-good win on Thursday for the A’s was followed by three straight one-run defeats, with Sunday’s 4-3 loss to the Mariners shrinking their lead over Seattle for second place in the AL West and the second AL Wild Card spot to just 1 1/2 games.

“This one stings for sure,” said A’s starter Cole Irvin, who turned in the shortest start of his career after allowing four runs in four innings. “Last night stung. Anytime you lose a one-run game against a team in your division, and on top of that, fighting for the Wild Card spot in your possession, it’s not easy to swallow. We’re gonna have to bounce back here and collect ourselves.”

A slumping offense was the theme of the series for the A’s, continuing on Sunday. Even after Irvin’s struggles to put Seattle’s hitters away in the third -- when four runs allowed on three straight two-out hits, flipping a 2-0 A's lead to a 4-2 deficit -- Oakland had plenty of time to come back. But in striking resemblance to their one hit collected after the third inning in Saturday’s loss, the A’s mustered just two hits after Matt Olson’s solo homer in the third inning.

The offensive struggles for the A’s have lingered since their return from the All-Star break. They’ve scored 33 runs in the nine games since, which ties for second-fewest in the Majors over that span. The woes at the plate are largely responsible for what could turn into just their second losing month dating back to 2018, now holding a record of 8-11 in July.

“We haven’t been playing the best this month,” Olson said. “It’s part of it. We still are in a decent spot for how we’ve been playing. We’ve built up a little bit of cushion that is dwindling away a little. 

“As tough as it’s been, we know we’re a team that can get hot or ride it out. We just need a big hit or a big game. Something to spark us a little bit and get rolling.”

Olson has done everything he can to carry the club’s offense on his back. Since his return from the All-Star break, the All-Star first baseman has quickly put the post-Home Run Derby slump myth to rest.

Sunday’s solo blast off Mariners starter Marco Gonzales in the third was Olson’s 27th of the year and fourth in the last six games. In the nine games back from the break, Olson is hitting .333 (11-for-33) with four homers, three doubles and seven RBIs.

But Olson can’t do it all on his own. He needs a helping hand in the lineup, which could come from an external source before Friday’s Trade Deadline. There’s also the issue that the bats currently around him in the lineup have been underperforming for most of this season, specifically Matt Chapman and Ramón Laureano, two key pieces to the A’s offense who remain hitting well below their career averages after Sunday’s loss.

“We have been a second-half team, and there’s no reason that we can’t [do that again],” Olson said. “We’ve still got a ton of baseball left. It’s a big hit away or a blowout away, just something to get a little momentum. There’s nothing that looking in the past is going to do for us. Just learn from it, move on and go win some ballgames.”

It feels an awful lot like gut-check time for the A’s. Now having dropped seven of their last 10 series, things won’t get any easier as they head to San Diego for a two-game series against an already potent Padres lineup that was bolstered on Sunday with the addition of All-Star second baseman Adam Frazier via trade.

But before that series gets underway on Tuesday, the A’s get an off-day Monday in San Diego, a chance for them to perhaps cleanse away their recent rut.

“A couple of us have talked about jumping in the water there in San Diego,” Irvin said. “There might be a few of us that go to the beach and relax, try to keep our mind straight. We’re just a little off right now and need a little pick-me-up. I think we’ll be able to regroup and have a good week, and next week we’ll see where we’re at.”