SEATTLE -- The Mariners got almost exactly what they wanted out of starter Yusei Kikuchi, who rebounded from one of his toughest starts of the season. Instead, it was the bullpen that had a shaky outing on Sunday afternoon.

A ninth-inning two-run homer from Jarred Kelenic wasn’t enough to mount a late rally as Seattle fell to Arizona, 5-4, at T-Mobile Park. It was the Mariners' second straight defeat against the National League-worst D-backs, giving Seattle a disappointing series loss as it was hoping to solidify its position in the postseason chase.

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The Mariners are now three games back of the Blue Jays and Red Sox, the two teams atop the American League Wild Card standings. Seattle had been only one game out of the second Wild Card berth after Friday's win. Now, it begins a three-game home series against Boston on Monday.

“You’re hoping to do a little bit more against the Diamondbacks offensively,” Mariners manager Scott Servais said. “Some days it’s there, some days it’s not. We’re looking forward to the next series. We can’t do anything about what just happened. It’s over. We have to look forward.”

Before Sunday’s game, Servais said he was hoping for five competitive innings from Kikuchi, who gave up six runs (four earned) and didn’t get out of the second inning in his previous start at Houston. Servais met with Kikuchi leading up to this outing to try to help his pitcher regroup.

“We sat down a couple times actually, and he mentioned to me that I didn’t have to necessarily worry too much about the result of today. He told me to just go out and compete and be aggressive,” Kikuchi said. “I think that advice helped a lot. Took a lot of weight off my shoulders.”

Kikuchi showed that aggressiveness early, throwing a first-pitch strike to the first seven batters he faced and 15 of the first 21. He credited catcher Tom Murphy’s game-calling for helping him keep the D-backs off balance, as he struck out eight and allowed only one run. One of Kikuchi's biggest moments came in the fourth, when he escaped a one-out bases-loaded jam by striking out Henry Ramos and Seth Beer.

With the game tied at 1 after five innings, Servais turned to his bullpen, which has been one of the main reasons for the team’s success this year. However, left-hander Anthony Misiewicz gave up hits to all four batters he faced in the sixth, allowing three runs as Arizona took a 4-1 lead.

“They jumped on him early,” Servais said. “I think it was three pitches, and you looked up and they had a couple guys in. Guys whacked the first thing they saw, and after that, we were fighting uphill the rest of the day.”

The Mariners missed an opportunity to take back the lead in the sixth, as they loaded the bases with two outs before Luis Torrens grounded out to end the inning. Then, right-hander Erik Swanson gave up a run on a homer to Ketel Marte in the seventh that pushed the D-backs' lead to 5-2.

Seattle's runs came from a trio of homers -- Mitch Haniger's solo shot in the fourth (extending his career-high homer total to 32), Dylan Moore's solo home run in the sixth and Kelenic's two-run blast in the ninth.

Kelenic worked the count full before depositing the ninth pitch from right-hander Taylor Widener into the upper deck in right field. It came off Kelenic's bat at 108.3 mph, per Statcast, marking the second hardest hit ball of his big league career thus far.

“When Jarred squares it up, he’s got as much raw power as anybody on our team,” Servais said.