Nationals second baseman Danny Espinosa catches a pop ball for the third out against the Cincinnati Reds in the third inning as right fielder Jayson Werth stays out of the way. (Jacquelyn Martin/AP)

On the final pitch of the fifth inning Wednesday night, a 91-mph sinker, Cincinnati Reds outfielder Jay Bruce lofted a lazy flyball to right field. He looked down at his hands and saw only the handle and knob of his bat still there. Washington Nationals starter Ross Detwiler had sawed off the rest of it.

For six innings, Detwiler threw 95-mph sinkers, late-breaking backdoor curveballs and a keep-them-honest change-up. He was nasty, maybe more than he had ever been in the majors. For one night, Detwiler also had little to show for it.

Before 20,374 at Nationals Park, Washington lost, 2-1, because Reds ace Johnny Cueto dominated for eight innings, a furious rally fizzled suddenly in the ninth and Joey Votto, the reigning National League MVP, blasted the one mistake Detwiler made into the visitors’ bullpen into the first inning. Nationals officials still had reason to sleep happy. Detwiler’s stellar performance meant more to them than the difference between 21 and 20 games out of first place.

“I was fortunate to play with him back in the minor leagues, and I saw what he could do,” shortstop Ian Desmond said. “I saw him when he was throwing 96, 97. I think tonight was a great step in the right direction. I’m definitely optimistic.”

After a disappointing start in Chicago, Detwiler rebounded with perhaps the best of his career. He struck out a career-high seven batters and walked two, allowing one run on seven hits while tying another career high with 103 pitches. Perhaps more than any of his previous 22 major league starts, Detwiler showed the pitching arsenal that convinced the Nationals to draft him with the sixth overall choice in 2007.

The Nationals almost toppled the Reds in the ninth. Ryan Zimmerman knocked Cueto out of the game by smoking the first pitch he threw over the left-center field fence. It was Zimmerman’s eighth home run of the season and second in as many games.

Reds closer Francisco Cordero replaced Cueto and walked Jayson Werth with one out. Danny Espinosa scorched a line-drive single to right. When Jonny Gomes grounded to the hole and shortstop Paul Janish bobbled the ball, the Nationals had the bases loaded with one out.

Up came Wilson Ramos. The only thing he could not do is exactly what he did: Ramos swung at the first pitch, a slider low and away, and grounded it to Brandon Phillips at second. He started a game-ending 4-6-3 double play.

The run reliever Sean Burnett allowed in the eighth inning loomed larger than it had at the start of the ninth. But Ramos had swung at a tough pitch that he didn’t have to.

“The pitcher is in a jam,” Nationals Manager Davey Johnson said. “I want to be aggressive, but we need to smart-aggressive, looking for balls in our area. And we haven’t been consistent doing that basically all year. We need to get better in that.”

From the start, Detwiler dominated with a combination of power and finesse. He struck out the first two batters he faced, Phillips and Dave Sappelt, both swinging at curveballs. Detwiler fell behind Votto with a 3-1 count and tried to throw a 95-mph fastball by him. Votto launched it to the opposite field, over the fence in left.

“If I don’t fall behind,” Detwiler said, “I think I can throw a better pitch.”

Detwiler needed to work around only once, when he loaded the bases with one out in the third. After getting ahead of Bruce with two strikes, Detwiler fired a searing, 95-mph sinker, down and inside. Bruce swung over it for strike three.

“Not too many times do you look up there and see a lefty throwing 94, 96,” Werth said. “He’s got good stuff.”

When Detwiler got Miguel Cairo to pop up to Espinosa in shallow right field, he had wiggled out of the jam. He had also matched his career high for strikeouts after only three innings. When he struck out Cueto in the fourth, he had a new career best.

After his start, Detwiler said he hoped to pitch deeper into his next start. It was the kind of night that made you wonder what else he could do.