SEATTLE -- The Philadelphia Phillies haven't had many highlights this season.

Wednesday afternoon's game at Safeco Field certainly qualifies as one.

Andrew Knapp drove in the go-ahead run with two outs in the top of the ninth inning as the Phillies rallied to defeat the Seattle Mariners 5-4 and sweep the two-game series.

Tommy Joseph tied it leading off the ninth against Seattle closer Edwin Diaz (2-3), hitting a 3-2 pitch over the Phillies' bullpen in left field for a solo home run, his 13th of the season -- tying Aaron Altherr for the team lead.

After striking out the next two batters, Diaz walked Cameron Perkins and then balked him to second. Knapp came up and lined a single into right field to score Perkins.

Knapp said his approach changed during the at-bat, after Perkins reached second.

"I wanted to try to get something to drive into the gap, but when he got to second I was just trying to get him in," Knapp said.

Philadelphia's Ricardo Pinto (1-0) pitched three scoreless innings of relief for his first major league victory, and Hector Neris worked a 1-2-3 ninth for his seventh save of the season.

"Certainly, Pinto was the key to that game," Phillies manager Pete Mackanin said. "He gave us three strong innings, kept the game close and really pitched well for a young kid."

The Phillies (26-51) won a road series for the first time since April 18-20 against the New York Mets and posted a road sweep for the first time since June 27-29, 2016, at Arizona.

"I think the guys are tired of losing," Mackanin said. "They've been in so many games ... it's like, 'C'mon, let's win some.'"

Seattle (39-41) lost its fourth in a row and failed in its bid to return to the .500 mark.

"Usually a one-run lead in the ninth with Eddie Diaz out there, you're feeling pretty good," Mariners manager Scott Servais said. "He wasn't on top of his game.

"That's the life of a closer. When you don't get the job done, there's no worse feeling than to let your teammates down."

Diaz's blown save spoiled a solid outing from Mariners ace Felix Hernandez

Making his second start since spending nearly two months on the disabled list with inflammation in his right shoulder, the right-hander allowed three runs on five hits in six innings. He walked three and struck out five.

All three runs against Hernandez came in the third inning, two on a home run by Ty Kelly, a former Mariners farmhand.

"Felix regathered (himself) and got deep in the game," Servais said. "It was a good effort by him."

James Pazos and Nick Vincent each pitched a perfect inning of relief of Hernandez before Diaz blew it in the ninth.

Kyle Seager, Danny Valencia and Robinson Cano hit solo shots for the Mariners, all against Phillies starter Mark Leiter Jr.

Cano's 413-foot homer to right-center field leading off the bottom of the fifth inning snapped a 3-3 tie. Cano's 14th home run of the season tied him with Nelson Cruz for the team lead.

The Mariners had evened the score an inning earlier, as Seager led off with a 400-foot shot, his ninth of the season, that landed halfway up the lower level in right field.

An out later, Valencia blasted a 431-foot homer into the second deck in left field make it 3-3. It was Valencia's eighth home run of the season.

The Mariners took a 1-0 lead in the first as Jean Segura led off with a single, stole second and moved to third on a throwing error by catcher Knapp, who was trying to nab Segura at second. With two outs, Cruz hit a run-scoring single up the middle.

"We won, so great," said Leiter, who allowed four runs on nine hits in five innings. "Really, the goal as a starting pitcher is to try to keep the team in the game as long as you can."

The Phillies answered in the third, as Knapp reached on an infield single and No. 9 hitter Kelly hit a two-run homer to right field. It was Kelly's first home run of the season and the second of his major league career.

Philadelphia wasn't done, as Daniel Nava and Freddy Galvis hit back-to-back singles. A one-out walk to Joseph loaded the bases.

Odubel Herrera grounded to second baseman Cano, who flipped to Valencia at first for one out as Nava scored to make it 3-1.

"This gives us confidence to know we're able to come back," Knapp said. "We don't have to try to do too much, just keep putting together good innings.

"It's been a tough stretch, but we have some good ballplayers."

NOTES: Phillies RF Aaron Altherr doubled in the first inning to extend his hitting streak to 10 games. ... Mariners RHP Felix Hernandez moved into 50th place in major league history in strikeouts with 2,297, surpassing Dwight Gooden (2,293). ... Seattle completed a 5-4 homestand, winning the first five games and losing the last four. ... The Mariners announced LHP Drew Smyly, who hasn't pitched this season, will undergo Tommy John surgery next week and miss approximately 12-15 months. ... The Phillies and Mariners are both idle Thursday. Philadelphia opens a three-game series Friday in New York against the Mets. RHP Ben Lively (1-2, 3.90 ERA) is scheduled to start for the Phillies. The Mariners head to Anaheim for three-game series against the Los Angeles Angels. RHP Sam Gaviglio (3-2, 3.38) is set to start the opener Friday.