Aug 18, 2017; San Diego, CA, USA; Washington Nationals center fielder Michael Taylor (3) makes a catch at the wall on a ball hit by San Diego Padres third baseman Yangervis Solarte (not pictured) as right fielder Andrew Stevenson (45) assists during the second inning at Petco Park. Mandatory Credit: Jake Roth-USA TODAY Sports (Jake Roth/Usa Today Sports)

A glum Dusty Baker wasn’t quite sure what to expect from Matt Grace a couple hours before the left-hander made his first career major league start Friday night. Max Scherzer, the Washington Nationals’ ace, was supposed to pitch against the San Diego Padres. It was supposed to be another opportunity for him to pad his Cy Young credentials against a team he thoroughly dominated earlier in the season. It was supposed to be a rare relatively stress-free night for Baker, the man whose job is to manage Nationals through their extraordinary slew of injuries.

Instead, Grace, a solid left-hander whose starting experience since he was converted to reliever in 2013 was limited to one spot start for Class AAA Syracuse in April, was suddenly pressed into action. Baker hoped he would give him three innings. Grace exceeded those expectations. The Los Angeles native, whose family took a train Friday down to San Diego to attend the game without knowing he would start, tossed 4⅓ scoreless innings before five relievers, all holdovers who predate the midseason bullpen renovation, combined to close out a 7-1 victory.

“There’s nothing else to be done in that situation,” Grace, 28, said. “Do what you can to contribute. I haven’t really felt like I’ve been contributing much as of late, so to take advantage of that opportunity and at least do something for a team win there was nice. As a bullpen as a whole, you take it as it comes and get after it.”

Grace, who was drafted as a starter in 2010, didn’t prepare like a starter Friday despite being notified of the change in plans before batting practice. He kept to the same routine he’s established as a reliever. The only difference was, perhaps, the extra nerves early. Those were swiftly discarded as he began his night with two perfect innings on 19 pitches.

The early efficiency afforded leeway, which permitted him to pitch into the fifth inning. Once there, he retired the left-handed hitting Cory Spangenberg before he was pulled after 52 pitches, one shy of his major league career high. He yielded two hits. He walked one and posted a strikeout. He received some help from the defense behind him, including center fielder Michael A. Taylor, who robbed Yangervis Solarte of a home run with a leaping catch on the warning track in the second inning. It was a commendable impression of Mad Max, one with more contact and less snarling but similar results.

“Oh, man,” Scherzer said. “He threw the ball great. To be able to do that in a bind. . . . For him to go out there and give us 4⅓ , that’s exactly what we needed. I really put the bullpen in jeopardy tonight and for him to be able to deliver what this ballclub needed, that really did a number for our team.”

While Grace set the tone on the mound for the 73-47 Nationals, a few other fill-ins provided the run support. Howie Kendrick, acquired last month in a trade with the Phillies, began the game with a solo home run off Padres right-hander Luis Perdomo and added an RBI single in the seventh to continue his blistering tenure was a National. Adam Lind, starting for Ryan Zimmerman at first base, smacked an RBI single in the sixth. Alejandro De Aza, called up on Wednesday, knocked in a run and scored another. Right fielder Andrew Stevenson, who began the season with Class AA Harrisburg, singled and scored.

For good measure, Daniel Murphy (RBI single) and Anthony Rendon (sacrifice fly), two of the few healthy regular starters, added a couple insurance runs in the ninth. It was a collective effort with help from a bunch of players that weren’t on Washington’s Opening Day roster, the kind that the Nationals have relied on in recent weeks to sustain their mammoth lead in the National League East.

It then fell on the bullpen to piece together the remaining outs. Shawn Kelley was the first reliever Baker called upon, replacing Grace with one out in the fifth. It was the right-hander’s first outing since June 16, and, like most of his outings before he landed on the disabled list with a trapezius strain, Kelley surrendered a home run. It was the second batter Kelley faced, Dusty Coleman, a 30-year-old rookie, who smacked a solo shot to left field to cut Washington’s lead to 2-1. It was the 10th home run Kelley has allowed this season in 18⅔ innings.

But from there, Joe Blanton, Oliver Perez, Matt Albers and Sammy Solis combined to hold San Diego (54-68) to one hit and two walks over the final four innings. The quintet finished off what one of their relief corps comrades had started without an appearance from any of the three relievers — Sean Doolittle, Brandon Kintzler and Ryan Madson, one of the 13 Nationals on the disabled list — acquired in July to displace them. It went almost exactly how Baker hoped it would.

“They did a great job,” Baker said. “Things just sort of worked out.”