WASHINGTON -- The Nationals are giving closer Sean Doolittle a breather in the midst of his roughest stretch of the season, putting him on the 10-day injured list with right knee tendinitis on Sunday morning.

The move comes one night after one of the worst outings of Doolittle’s career, when he surrendered a three-run lead in the ninth inning on just 13 pitches, giving up four hits and three homers while retiring just one batter. It prompted a meeting with Doolittle, who has a history of knee injuries, manager Dave Martinez and the team’s medical staff Sunday morning where the Nats felt like it would be best to sit him down.

Kyle McGowin has been promoted from Double-A Harrisburg in his place, likely to provide some length for the afternoon following Saturday’s 14-inning, 15-14 loss to the Brewers.

“We want to get it right, so we put him on the IL,” Martinez said. “Hopefully, it won't take as long, he's back in 10 days and when he does come back, he's our closer. And I reiterated that to him. He's our closer, but we've got to get him right.”

In Doolittle’s absence, Martinez said he expects to use matchups to close games in the ninth inning, relying on a combination of Daniel Hudson, Hunter Strickland and Fernando Rodney.

Martinez continued to throw his support behind Doolittle as the team’s closer despite his recent scuffles. In his last 10 outings, Doolittle has given up seven home runs (his previous career high was six for an entire season) and 12 runs, nearly doubling his ERA from 2.72 to 4.33.

Doolittle has also acknowledged that he has been feeling fatigued after recent appearances. He appeared in his 54th game on Saturday, his most since 2014, and was on pace for a career high in appearances. He was noticeably diminished Saturday night, with a fastball that averaged just 91.8 mph, down from its usual 93.6-mph velocity this season.

“I really felt like, and he felt like, he couldn't get onto that front side like he wanted to,” Martinez said. “When that happens, all of a sudden you start favoring one thing. My biggest concern is hurting something else, which is his arm.

“We talked, and I told him, 'You're not letting anybody down.' But we've got to get you right. He wanted to pitch, he wants to pitch. I said, ‘I want you to pitch. And I want you to pitch the ninth inning in close games for us.’ But I want to make sure that you're healthy, and that's our biggest concern.”

That Doolittle is on pace for a career high in appearances is a product of Washington’s beleaguered bullpen for much of the first half, when Doolittle shouldered the majority of the workload to keep baseball’s worst bullpen afloat. And Doolittle is on such a pace because before Sunday he had avoided a lengthy stint on the injured list, which he hasn't been able to avoid in recent seasons.

But Martinez was still left to defend his heavy usage of Doolittle on Sunday morning, especially since the Nats overhauled their bullpen following the Trade Deadline. Despite how open Doolittle has been about his fatigue recently and the number of new options Martinez has to pitch late in games -- Strickland and Hudson have both been lights-out since joining the Nats -- Doolittle has still appeared in eight games this month, during which he owns a 12.86 ERA.

“Doolittle's the closer. He's the closer of this team,” Martinez said. “We've said that before. This is based on conversations with Doo. If he's available, as we talked about, then he's going to pitch the ninth inning. He's always been in the game when he said he was available to pitch.”