PITTSBURGH (AP) -- The Washington Nationals' hitters spent a lot more time Friday night walking slowly back to the dugout than running the bases, striking out a total of 14 times.
A.J. Burnett allowed one run and struck out nine in seven strong innings, and call-up Jordy Mercer hit a tiebreaking home run to lead the Pittsburgh Pirates to a 3-1 victory over the Nationals on Friday night.
Relievers Mark Melancon and Jason Grilli combined for five strikeouts as each pitched one scoreless inning to finish off the seven-hitter with Grilli earning his 12th save.
"We've got good hitters but we're striking out more than we should," said Nationals manager Davey Johnson, whose team has averaged eight punch outs a game in getting off to a 15-15 start. "I don't know if it's being aggressive early in the count or not, but I do feel we're trying too hard to make things happen. Everyone just needs to relax a little bit."
Nationals first baseman Adam LaRoche attributed the abundance of strikeouts on Friday night to the Pirates' pitchers.
"We were going up against some nasty pitchers who strike guys out," LaRoche said. "Burnett's fastball kept coming back over the plate and he got a lot of called third strikes on it."
Burnett (3-2) gave up five hits and one walk in winning his third straight game after going 0-2 in his first three starts. He also raised his NL-leading strikeout total to 57.
"Strikeouts are always good to have and I like to put people away," Burnett said. "There will be some nights where I won't have many strikeouts, so you take them when you can get them."
Mercer's two-run home run off Ross Detwiler (1-3) in the fifth inning put the Pirates ahead 3-1. Mercer was recalled from Triple-A Indianapolis before the game when second baseman Neil Walker was placed on the disabled list with a right hand injury.
Detwiler went five innings and gave up three runs and six hits while walking two and striking out five.
The Pirates won for the fourth time in six games and the Nationals lost for the fourth time in six games.
Andrew McCutchen had three hits, including a home run, for Pittsburgh. Gaby Sanchez and leadoff man Starling Marte added two hits apiece.
LaRoche went 2 for 3 to equal the number of hits he had in his previous 11 games and 38 at-bats.
"I'm starting to feel better at the plate," LaRoche said. "My front foot is getting softer. When I land hard on my front foot in my swing, my head turns and I don't see the pitch nearly as well."
McCutchen hit a solo shot off Detwiler in the first inning for a 1-0 lead. The center fielder has 10 home runs against Washington in 24 games.
"It's kind of weird, but it was the same exact pitch on both home runs and it's what ended up beating me," Detwiler said. "I tried to get a fastball to the outside corner and they both cut back over the plate and their guys hit them, which is what they're supposed to do and what they get paid for."
The Nationals tied it in the fourth on Danny Espinosa's RBI single. It was just the second hit in the last 23 at-bats for the second baseman.
"It's good to see Danny knock in a run," Johnson said. "He has such a high ceiling. I want him to realize that he's capable of accomplishing so much more."
NOTES: Washington activated 3B Ryan Zimmerman from the 15-day disabled list before the game and he went 0 for 4 with four strikeouts. INF Anthony Rendon was sent to Double-A Harrisburg of the Eastern League to make roster space. Zimmerman had been on the disabled list since April 18 with a strained left hamstring and the Nationals were 6-8 in his absence. ... Washington RF Jayson Werth did not play and is likely to miss the three-game series with a strained right hamstring. ... Nationals RHP Stephen Strasburg (1-4, 3.16) looks to snap his four-game losing streak Saturday when he faces left-hander Jeff Locke (3-1, 2.83), who has pitched 13 scoreless innings while winning his last two starts.
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