Washington’s Stone Garrett celebrates with Dominic Smith after hitting a solo home run against the Boston Red Sox in the fourth inning Wednesday at Washington, D.C. Andrew Harnik/Associated Press

WASHINGTON — Keibert Ruiz hit a tie-breaking three-run homer in the eighth inning, Stone Garrett homered twice for the first time in his career, and the Washington Nationals beat the Boston Red Sox 6-2 on Wednesday night.

After Lane Thomas singled and Joey Meneses was hit by a pitch leading off the eighth, Ruiz drove an 0-1 change-up from Garrett Whitlock (5-4) to right-center to make it 5-2. Two pitches later, Garrett hit a no-doubt, 442-foot liner to center, his ninth of the season. Garrett also homered leading off the fourth.

MacKenzie Gore allowed one hit while pitching into the seventh inning for Washington but departed after 85 pitches. The second-year lefty appeared to have some discomfort on his pitching hand after throwing a first-pitch ball to Trevor Story with one out.

Jordan Weems came in and retired Story on a double-play grounder but gave up a tying, two-run homer to Pablo Reyes in the eighth that awakened the pro-Red Sox crowd of 26,507. Jose A. Ferrer (2-0) got the final two outs of the inning.

Michael Chavis hit his second homer of the season for the light-hitting Nationals, who entered the night with the second-fewest homers in the majors, ahead of only Cleveland.

Boston, which came in trailing AL East rival Toronto by three games for the final wild-card spot, fell to 7-7 in August. Rebuilding Washington has won 13 of 16 at home and improved to 20-13 since July 8.

Gore retired the first 10 batters, struck out seven and faced one batter over the minimum through six. He outdueled veteran lefty James Paxton who gave up two runs on five hits in six innings.

NOTES: Red Sox first baseman Triston Casas had six unassisted putouts — three grounders, three popups — through four innings, including all three in the first. … RHP Tanner Houck (facial fracture) is expected to rejoin the team Monday after his final rehab outing Wednesday. … SS Adalberto Mondesí (left knee surgery) has been shut down from baseball activities after not feeling great while ramping up. … RHP Zack Kelly (right elbow surgery) threw a 25-pitch bullpen on Wednesday.