WASHINGTON -- Keibert Ruiz’s first career walk-off home run rewarded a gritty performance from starter Jake Irvin as the Nationals topped the Oakland A’s, 3-2, Saturday night at Nationals Park.

Ruiz got hold of A’s reliever Lucas Erceg’s first pitch in the bottom of the ninth, driving a 97 mph fastball over the right-field wall for his 14th homer of the season, capping the Nats' 22nd comeback win of the season. The backstop has been in a nice groove, hitting .346 over his last seven games.

"Just a great swing,” said manager Dave Martinez. “Aggressive, in the zone, was ready, got ready on time, stayed back and [drove] the ball. He's been playing well. Both sides. His defense has been really good. He's starting to swing the bat like we know he can. He's been awesome."

Following the game-winning blast, Ruiz was showered with Gatorade by his teammates as they chased him around the infield, soaking in the cheers from the home crowd on a muggy Saturday night.

"I was looking for a good pitch to hit and I got it and I put a good swing on it,” Ruiz said. “I can't describe the moment. It's something that I've been dreaming about for a long time, and [I'm] just really grateful."

Lane Thomas tied the game with a pinch-hit single in the eighth. He was a late scratch from the lineup due to a sore right wrist, but arrived just in time to even the score at 2-2.

The Nats’ first run was set up in the second inning by a bizarre single from Ildemaro Vargas, who reached base when A’s starter Luis Medina did not cover first base on a sharp comebacker to the mound. Vargas was safe with a single when Medina did not touch the bag and later scored on a fielder’s-choice groundout by Alex Call.

"I've never seen that before,” Martinez said. “I've been doing this a long time. He's a very smart baseball player. I've said that a lot about him. He plays the game the right way. A lot of guys wouldn't see that. He saw it and took off right in the perfect time and beat him to the base."

The inning was kept alive thanks to Blake Rutherford’s first Major League hit. He later added another single and a walk after starting the season 0-for-16.

"I don't know if it’s really sunk in,” Rutherford said. “It was a surreal moment. I can't really thank all these players [enough, and] all the coaches for having my back for telling me to keep going, to keep pushing. Every single one of them is picking me up every single day and I couldn't be more thankful for that.

"To have my brother fly in and my girlfriend here to be able to see it ... Not as many as the debut, but to still have people here who were part of the journey is special and I'm extremely grateful for them and for all my family back home watching."

The only runs Irvin allowed scored on a pair of solo shots to JJ Bleday and Brent Rooker.

Irvin was outstanding after four relievers had to appear in Friday’s opener. Irvin fired 99 pitches and used his potent sinker and elusive curveball to register six strikeouts while walking none, matching a season-high 6 2/3 innings and scattering seven hits.

"I think the biggest thing was after yesterday having to lose a lot of guys out of the pen, [I] just wanted to get deep in the game, throwing strikes early, [and] trying to keep guys off balance,” Irvin said.

Washington has won each of Irvin’s last five starts.

The Nationals left 12 men on base and went just 2-for-15 with runners in scoring position, but still found a way to earn their 52nd win, matching the New York Mets’ win total.

It was again all about creating multiple opportunities for Martinez, whose club is now an incredible 12-8 when stranding 10 or more runners.

"We left a lot of guys on base today,” Martinez said. “I definitely didn't want to play anymore. Our bullpen has been beat up a little bit, so [for Ruiz] to go out there and hit that first pitch for a homer was awesome. I mean, it really was. The guys were [pumped] up. It was a lot of fun."