BALTIMORE - Coming off his worst start of the season, Max Scherzer wasn't willing to wait any longer than necessary to get back on the mound.

The heck with the All-Star Game, which is Tuesday night. Scherzer was delighted to have the opportunity to pitch Sunday, and now the Nationals' ace has a feel-good memory to take into the break.

Scherzer ended his impressive first half with another dominant performance, taking a three-hitter into the ninth inning to lead Washington to a 3-2 victory over the Baltimore Orioles.

Following an uncharacteristic dud in which he gave up five runs in 4 2-3 innings against the Reds, Scherzer (10-7) allowed only three base runners until Adam Jones hit his second homer of the game with two outs in the ninth.

Drew Storen entered and struck out Chris Davis to earn his 27th save.

"After the start against Cincinnati I wanted to come out here today and pitch as well as I can, pitch as well as I'm capable of," Scherzer said.

Scherzer (10-7) allowed four hits, struck out seven and walked none. He retired 14 straight after allowing a first-inning homer to Jones.

"A lot better than the last time out. A lot better," manager Matt Williams said.

This outing fit accordingly into a first half that included a no-hitter, a one-hitter and 17 starts of at least six innings.

Scherzer was selected to the NL All-Star team, but he chose not to pitch in Tuesday's game. Though the right-hander certainly deserves a chance to show his stuff on the grand stage in Cincinnati, the Nationals gave him a $210 million, seven-year contract in January to help the team win the NL East and excel in the post-season.

"He's a team guy," teammate Dan Uggla said. "There is never a doubt he wanted to pitch today, although I'm sure he wanted to pitch in the All-Star Game. The team came first."

Scherzer has accounted for more than a fifth of first-place Washington's 48 wins, and his 2.11 ERA ranks among the league leaders.

He outpitched Orioles starter Wei-Yin Chen (4-5), who allowed three runs and eight hits in a career-high tying eight innings.

"He's a great pitcher and a player that I respect a lot," Chen, speaking through an interpreter, said of Scherzer. "Watching him pitch, I learn a lot from him. Today, his pitching was just great."

Baltimore reached the break at .500, no small disappointment for the defending AL East champions. The Orioles have lost 10 of 13 since June 28, when they were in first place with a 41-34 record.

"I think our best baseball is ahead of us," manager Buck Showalter said.

Yunel Escobar had three hits and scored a run for the Nationals, who won two of three from their neighbouring rivals.

This game started well for Baltimore, performing before a third straight sellout crowd at Camden Yards.

With runners on second and third with two outs in the top of the first, Davis made a nice running catch of Wilson Ramos' liner to right-centre.

Scherzer struck out the first two batters in the bottom half before Jones hit a 1-2 pitch into the seats in left field.

Jones' second homer was his 180th with the Orioles, pushing him past Frank Robinson into eighth place on the team's list.

Washington used three straight two-out hits to take a 3-1 lead in the fourth. After singles by Escobar and Clint Robinson put runners on first and second, Uggla singled in a run and Tyler Moore followed with a two-run double.

Scherzer made the lead stand up to avoid a third straight loss for the first time since May 2010.

SERIES NOTES

The Orioles lead the series 36-32, including 23-14 at home. They meet for three games in Washington in September. The Nationals' lone series win over a season came in 2007.

TRAINER'S ROOM

Nationals: RHP Stephen Strasburg (oblique) won't return from his second stint on the DL unless he's close to 100 per cent. "He's healing up. Don't want to rush him," Williams said.

Orioles: Davis was back in the lineup after missing Saturday's game with a stomach virus.

ON DECK

Nationals: Washington returns from the break Friday to launch a three-game series against the NL West-leading Los Angeles Dodgers.

Orioles: Baltimore opens the second half with a nine-game road trip that begins Friday night in Detroit.