WASHINGTON -- Tampa Bay Rays manager Kevin Cash had good reason to be happy. His team remained in first place in the American League East, improved to 19-11 on the road and finished a two-city series by beating the Washington Nationals for the third time in four days.

But without being asked, the rookie manager sent out his well wishes to Nationals slugger Bryce Harper after a 5-3 win Thursday. Harper, the right fielder who ranks among the league leaders in several offensive categories with 22 homers and 53 RBIs, injured his left leg on a throw in the sixth inning. He has a mild left hamstring strain and will be evaluated Friday.

"Hopefully he is OK. It didn't look good," said Cash, whose club has won eight of its last 11 games.

Harper left the game after making a throw after an RBI single by shortstop Asdrubal Cabrera. With runners on first and second and one out, Cabrera lined a single to right as second baseman Logan Forsythe scored to tie the game at 3-3.

"We will see how he is tomorrow," Washington manager Matt Williams said of Harper.

Harper's throw sailed into the Tampa Bay dugout as right fielder Steven Souza, Jr. was awarded home plate to make it 4-3 as Cabrera was awarded third. Harper stayed on the ground for several minutes while holding his left leg. He walked off the field gingerly on his own power and was replaced in right field by Clint Robinson.

"I have had problems with my left leg before," Harper said. "It was definitely really scary. We will see how it feels tomorrow."

The Rays took a 5-3 lead on an RBI triple by pinch-hitter David DeJesus later in the sixth. Three infielders for the Rays had at least two hits -- third baseman Evan Longoria, second baseman Logan Forsythe and Cabrera.

Tampa Bay won 14 of the last 15 road starts by Archer. The first-place Rays (38-30) won seven of their last eight games while Washington (34-33), which made three errors for the second day in a row, is 6-11 in the month of June.

Archer (8-4) allowed eight hits and three runs with two walks and three strikeouts in five innings.

"Arch did a nice job settling down," Cash said. "Typical Arch. We had some really nice at-bats. Our bullpen came in and finished it out. It is nice when they had some time off. It worked out good."

The loss went to Doug Fister (2-3), who yielded nine hits and five runs with no walks and three strikeouts in 5 1/3 innings. "I felt a lot better," said Fister, who came off the disabled list to make his first start since May. "It's a work in progress; I keep saying that. I'm pleased with where I am at."

Jake McGee pitched the eighth for the Rays and Brad Boxberger went the ninth for his 16th save.

Tampa Bay scored four runs in the sixth while Harper was injured during the rally. Joey Butler, a left fielder for the Rays, hit a solo homer to lead off the frame to cut the margin to 3-2.

"It put us one run closer," Cash said of the homer. "We pieced together a big inning more or less."

Washington third baseman Yunel Escobar had five hits and first baseman Danny Espinosa and center fielder Denard Span, who sat out Wednesday with back spasms, had two each.

The Nationals scored two earned runs in the first inning, as Harper had an RBI single and Espinosa drove in a run with a fielder's choice.

The Rays trimmed the lead to 2-1 with an RBI single in the second by first baseman Jake Elmore. Washington got the run back in the last of the second as Escobar singled to drive in left fielder Michael A. Taylor to make it 3-1.

"The bench has been tremendous," Cash said. "We picked the right guy" with the hit by DeJesus.

NOTES: The game was interrupted for 17 minutes because of light rain prior to the last of the fourth. ... Washington RHP Doug Fister was activated off the disabled list to start Thursday and RHP Taylor Hill (0-0, 3.75) was sent to Triple-A Syracuse. ... Washington will open a three-game series at home Friday with the Pittsburgh Pirates as RHP Joe Ross (1-1, 3.46 ERA) will face RHP A.J. Burnett (6-2, 1.89). ... Tampa Bay RHP Nathan Karns (3-3, 3.67) will start Friday against RHP Carlos Carrasco (8-5, 4.38) in Cleveland. ... Tampa Bay OF Steven Souza Jr. was honored with the 2014 Defensive Player of the Year GIBBY (Greatness in Baseball Yearly) Award by MLB.com. Souza made a diving catch in left-center on Sept. 28 to rob Miami's Christian Yelich of extra bases for the last out in the no-hitter by Washington RHP Jordan Zimmermann. Souza hit a homer against Zimmermann on Wednesday.