KANSAS CITY, Mo. -- Bryce Harper hit a three-run double and Jayson Werth had a two-run homer in a seven-run fourth inning as the Washington Nationals overcame a six-run deficit and held on to defeat the Kansas City Royals 11-10 on Friday night.
The Nationals have won four straight to even their record at 64-64. They are at .500 for the first time since July 19.
The Royals have lost six straight and nine of 11.
Tanner Roark (4-0), who was called up Aug. 6 from Triple-A Syracuse, pitched 4 2/3 scoreless innings, allowing one hit, to pick up the victory. He relieved Gio Gonzalez, who failed to make it out of the fourth.
Roark came in with two runners on and one out and the Nationals clinging to a one-run advantage but got Justin Maxwell to ground into an inning ending double play.
While the fourth was the big inning, the Nationals added three runs in the seventh and that became huge.
Ian Desmond, who went 3-for-5, led off with a single, Wilson Ramos doubled and Adam LaRoche walked to load the bases with none out. Tyler Moore stroked a run-producing single, his third hit of the game. Chris Getz's fielding miscue allowed Ramos and LaRoche to score unearned runs.
The Nationals had hoped to stay away from closer Rafael Soriano, who had pitched the previous three days, but he was summoned in the ninth after Drew Storen walked Alex Gordon and yielded a double to Eric Hosmer. Soriano yielded three runs, two scoring on a Maxwell single, before getting the final two outs for his 33rd save.
The Royals, who scored five runs while being swept by the Chicago White Sox, jumped out to a 6-0 lead after two innings.
Hosmer, a two-run shot, and Maxwell homered in a three-run first inning.
Jamey Carroll doubled in the second inning to snap an 0-for-16 slump since being acquired by the Royals in a trade. He scored on a Gordon double, and Hosmer and Billy Butler stroked RBI singles.
The six-run lead, however, evaporated quickly.
The Nationals got a run back in the third when Denard Span's two-out triple scored Anthony Rendon. Bruce Chen walked Ryan Zimmerman and Bryce Harper to load the bases, but Werth flied out to Maxwell in right to leave them loaded.
Chen was not so fortunate in the fourth when the Nationals sent 10 men to the plate in a seven-run inning. After a Rendon sacrifice fly, Span and Zimmerman each drew 10-pitch walks. Span fouled off six pitches, and Zimmerman fouled off four pitches with the bases loaded before walking, which scored LaRoche.
Harper cleared the bases with a double to tie the score at 6 and sent Chen to the showers. Louis Coleman, who had not allowed a run this season in 21 innings, replaced Chen and promptly gave up a home run to Werth on a full-count pitch.
Chen's final line was seven runs, six hits and five walks in 3 2/3 innings and 95 pitches.
Gonzalez gave up an RBI single to Salvador Perez in the fourth, cutting the Washington lead to one.
Gonzalez, who is winless in seven starts since a July 10 victory at Philadelphia, permitted seven runs (six earned) and nine hits, including two home runs, and three walks. That matched his briefest outing of the season. The other was July 31 at Detroit when he allowed 10 runs and 11 hits.
NOTES: The Nationals made a slew of roster moves on Friday. They traded OF David DeJesus after only four days with the club to the Rays for cash or a player to be named. They dealt C Kurt Suzuki to the Athletics for minor league RHP Dakota Bacus. LHP Xavier Cedeno and C Jhonatan Solano were recalled from Triple-A Syracuse. ... Royals OF Lorenzo Cain, who went on the disabled list with a pulled left oblique on Aug. 9, took some dry swings and did some light work on the field, but he is not expected to be back until mid-September.