Sean Doolittle was gassed, clenching his fists and letting loose a scream, then crouching on the mound after striking out Yadiel Rivera to finish off the Miami Marlins on Wednesday night.

It was, by any measure, a hectic save for the Washington Nationals’ closer. Doolittle loaded the bases. He gave up a run by hitting a batter. He got up to 33 pitches, a season high, and finally beat Rivera with a high fastball to sidestep disaster. Doolittle later admitted his heavy workload might have caused fatigue, and the July humidity didn’t help. But the larger point is that the Nationals cannot rely on just one reliever in big situations, as they have all year, or Doolittle will get burned out.

So about 16 hours later, in the series finale with the Marlins on Thursday afternoon, with Washington holding a three-run lead, 42-year-old Fernando Rodney rode the bullpen cart into a save opportunity. Doolittle was unavailable. Manager Dave Martinez had mapped out his relievers that morning, beginning with Tanner Rainey, then Wander Suero, then Jonny Venters and Javy Guerra when Suero wilted, then Rodney for the ninth. Auditions to be the Nationals’ setup man/secondary closer have been simple this season: Pitch a scoreless inning, and you get another chance and another and another until either your arm tires or you prove fit for the job. Trevor Rosenthal had failed and was released. Kyle Barraclough struggled, too, before landing on the injured list. Suero is in the midst of fumbling away his opportunity.

And Rodney, baseball’s oldest pitcher, might just be getting started.

“If he can do that and Doo can’t go, he’s going to be the guy,” Martinez said of Rodney on Thursday, and no one could have expected to hear that July 4.

What Rodney did, really, was enter a game with a lead and exit it without starting a fire. That may seem like a low bar — and it is — but it also makes him one of Washington’s relievers of the moment. Martinez has searched all year for anyone who can get outs with consistency, strand inherited runners and minimize the need for Doolittle every night. That pitcher has emerged only in flashes before waning, leaving the manager with a new puzzle to solve. Now the additions of Rodney and the 34-year-old Venters, however odd or uninspiring, seem to be pointing the bullpen in a better direction.

Rodney got two quick outs against the Marlins, allowed back-to-back singles, then got Harold Ramirez to ground into a forceout to push Washington into second place in the National League East at 45-41. His four-seam fastball got up to 99 mph on his second-to-last pitch. He used his change-up when in trouble and looked entirely calm in a jam. He has only recorded 327 saves across 17 major league seasons. And he has now finished three games for the Nationals, two saves and a mop-up inning of a 6-1 win, and he got a big double play to end the eighth Wednesday.

The veteran right-hander started this season with a 9.42 ERA in 14⅓ innings with the Oakland Athletics, so any progress should be viewed with apprehension. But these are encouraging signs.

“It’s a lot of trust. [Martinez] knows I can do my job in any inning they can give me,” Rodney said after Thursday’s win. “ ‘The closer’s down today,' he says. ‘You got it today.’ I feel good because he’s comfortable with how he’s been using me.”

How this translates to less work for Doolittle — and a fresher arm the rest of the way — is still tricky. Doolittle was unavailable Thursday because of how many pitches he threw in that rocky save Wednesday. Using Rodney in the ninth, in a three-run game, wasn’t the same as Martinez staying away from a rested Doolittle and crossing his fingers. But if Martinez can do that more and lean on Doolittle less in three-, four- or even five-run games, then Rodney’s importance will grow.

Doolittle, 32, has made 38 appearances with three games left before the all-star break. His career high is 70, when he was 26 in 2013, and he otherwise has been much lower because of injuries. And even though he’s the Nationals’ closer, they have often used him outside of save opportunities because few other relievers — if any — have been trustworthy. He has made four multi-inning appearances, all in April or May, and has topped 30 pitches four times. He leads the National League with 34 games finished. But 13 of those finishes were in non-save opportunities, meaning Martinez missed 13 or so chances to give Doolittle a day off.

Those will add up by the end of the season, especially with the Nationals back in contention, and especially with the postseason looking like a renewed possibility. By calling Rodney his “guy” when Doolittle is unavailable, Martinez also is implying that he could pitch the eighth and, just maybe, the ninth when Washington has a bit of a cushion. That’s the role Rosenthal was supposed to fill this season. Now it’s Rodney’s to lose, a plan that will be tested when the Nationals face the Philadelphia Phillies, Atlanta Braves, Colorado Rockies and Los Angeles Dodgers over five series coming out of the all-star break.

“Here’s a guy that’s done it and was really effective doing it,” Martinez said. “And you know he comes out and pumps strikes, that’s what he does, and I like what I’m seeing from him.”