BOSTON — The Washington Nationals finally started hitting the ball consistently. The problem was they couldn't do the same defensively.
The Nationals scored six runs in the fifth inning — two more than they had scored in any of their previous seven games — but also made three errors in an 8-7 loss to the Boston Red Sox on Tuesday night.
That came one day after Washington center fielder Michael A. Taylor let two balls drop for singles in a four-run inning that led to Boston's 9-4 win.
"We scored seven runs," Nationals manager Matt Williams said, "which is a good sign. And if you continue to kick the ball around you're going to lose. Bottom line."
Two errors by pitcher Blake Treinen helped the Red Sox score three unearned runs on no hits in the seventh as they took an 8-7 lead.
"It's the same recipe," Williams said. "If you put all the ingredients together the same way every time, then you're going to get the same meal."
The Red Sox had 11 hits, including Dustin Pedroia's solo shot, his third homer of the season. But the errors made the difference.
"It's not going to happen every day," Boston's Hanley Ramirez said, "but you've got to take advantage when that happens."
Ramirez reached first base on a fielding error by shortstop Ian Desmond before Shane Victorino was hit by a pitch from Matt Thornton. After Mike Napoli's flyout sent Ramirez to third, Treinen replaced Thornton and hit Allen Craig, loading the bases.
Treinen (0-1) fielded Ryan Hanigan's bouncer in front of the plate, dropped the ball as Ramirez scored, then threw it past catcher Wilson Ramos as Victorino came home with the tying run. Craig scored the go-ahead run on Brock Holt's groundout.
"I just felt like I got to it perfectly fine," Treinen said. "Then the transition in between my glove and my hand, I just bobbled it, it fell to the ground. I just kind of had to get rid of it quick and made a terrible throw."
Boston third baseman Pablo Sandoval left the game in the top of the sixth with a bruised left foot after being hit by a pitch in the bottom of the third. Manager John Farrell said the foot became sore as the game progressed but an examination showed no fracture.
Edward Mujica (1-0) got the win and Koji Uehara got his first save by finishing a perfect ninth — after Ryan Zimmerman's shot went just to the left of the left-field foul pole — one day after being activated from the disabled list.
Nationals starter Stephen Strasburg allowed five runs and 10 hits in 5 1-3 innings, leaving him with a 6.75 ERA.
Washington reached Justin Masterson for six runs in the fifth as they sent 10 batters to the plate.
Masterson retired leadoff hitter Yunel Escobar then loaded the bases when he hit Jayson Werth with a pitch, gave up a single to Harper and walked Zimmerman. Clint Robinson then singled in a run and another scored when Ramos grounded out. Desmond doubled in two runs before a triple by Taylor drove in two more, putting Washington ahead 7-5.
Masterson pitched in Fenway Park for the team he started his career with for the first time since being traded to Cleveland in July 2009 for Victor Martinez. "It was great," he said. "I was hoping it would be a little bit better, but it was just good. The fans here are just incredible."
Nationals: LF Jayson Werth played his second straight game after being activated from the DL following right shoulder surgery in January. He batted second, went 0 for 4 and is 0 for 7 this year.
Red Sox: SS Xander Bogaerts missed the game with a sore right knee. Farrell said he might be able to play in Wednesday's series finale. RHP Brandon Workman visited orthopedist Dr. James Andrews to check on his right elbow. Workman has been with Triple-A Pawtucket this season after going 1-10 with a 5.17 ERA last season in 19 games for Boston.
Gio Gonzalez (0-1) faces Wade Miley (0-0) in the finale of the three-game series. They last faced each other on Aug. 21 when Miley was with Arizona. Neither allowed a run — Gonzalez in seven innings, Miley in 6 2-3 — before Washington won in the bottom of the ninth when an error allowed the game's only run to score. It was Washington's 10th consecutive win.