PHILADELPHIA -- Not much has gone right for the Washington Nationals since the All-Star break. However, for a few hours Tuesday, two of the franchise's cornerstones showed how dominant they can be.

Stephen Strasburg allowed just one hit and tied a career high with 14 strikeouts, and Bryce Harper homered twice in a 4-0 win over the Philadelphia Phillies at Citizens Bank Park.

For Strasburg, it was a strikeout number he had not reached since his highly anticipated debut on June 8, 2010. For Harper, it was a continuation of his surge for the National League MVP award.

"You appreciate the effort and special talent they both have," Nationals manager Matt Williams said of the duo of former No. 1 overall draft picks. "And it can be that special on any given night."

Harper went 3-for-3 with a solo homer, two-run shot and an RBI single. The 22-year-old right fielder raised his home run total to 39, tied with Colorado's Nolan Arenado for the National League lead.

As masterful as Harper was with his bat, Strasburg was as excellent with his right arm during his eight-inning outing. Strasburg (9-7) notched his 19th career game with 10 or more strikeouts and second in a row after he struck out 13 New York Mets on Sept. 9.

Third baseman Cody Asche's leadoff single in the fifth inning was the only hit against Strasburg. The Phillies did not have a runner reach second base the entire game, and the only other batter to reach base was shortstop Freddy Galvis, who drew a first-inning walk.

"That's probably one of the best, if not the best pitched game I've seen all year," Phillies manager Pete Mackanin said in reference to Strasburg.

Strasburg, who has had two separate disabled-list stints this season, established his fastball early and then worked in his off-speed pitches later to keep Philadelphia hitters off-balance.

"It's a feel thing," Strasburg said. "You have to trust your instincts and go out there and battle."

Strasburg registered a whopping 30 swings and misses on his 105 pitches, and he struck out the side in both the fifth and seventh.

"He's a stud," Harper said of his teammate. "To be able to go out there and establish his heater early and establish his changeup also ... When the heater is down, they're going to chase that changeup down. He had everything working tonight, and it's special to play behind that."

After Strasburg's exit, Blake Treinen completed the one-hitter by throwing a perfect ninth inning.

Strasburg -- and many others -- have plenty of good things to say about Harper, too.

Harper's first-inning home run was a solo shot that just cleared the deepest part of the Citizens Bank Park fence off of Phillies starter David Buchanan.

Buchanan said, "I was trying to execute a curveball down in the zone and left it up. The guy's a good hitter, and he went with it."

Harper followed that with his 88 through 90th RBIs of the season. He hit a single that brought home third baseman Yunel Escobar in the third inning, and then a two-run shot in the eighth that also plated Escobar.

Harper entered the game leading the NL in on-base percentage, slugging percentage, on-base-plus-slugging percentage, batting average and runs -- and he boosted his stats in every category.

"He's matured as a hitter and as a player," Strasburg said of Harper. "When you have a professional approach like he does, you can see what his talent can do."

While the Phillies were shut out for the 12th time this season, Buchanan was solid. He allowed only the two runs off Harper's bat while working around three other hits. Buchanan (2-9) lasted six innings, struck out five and lowered his ERA from 9.11 to 8.49.

It was just the second time in 12 starts that Buchanan allowed fewer than three runs in a start this season, and the right-hander got inning-ending double plays in both the third and sixth innings.

Tuesday's win was the third in a row for Washington, which improved to four games over .500 (74-70). The Nationals gained ground in the NL East, as the New York Mets lost to the Miami Marlins, but Washington still trails the division it once lead by 8 1/2 games.

"I'll let you guys play the 'what if' scenarios," Strasburg said. "I'll just play it one day at a time and give it everything I got."

NOTES: Phillies 1B Ryan Howard was not in the lineup Tuesday after getting hit on the left knee in the field during Monday night's 8-7 loss to Washington. The team called it a contusion. Howard had two home runs and five RBIs in his last three games before the injury, including his 23rd homer of the season Monday. ... Phillies 2B Andres Blanco was penciled in the cleanup spot Tuesday, making his first start from the four-hole in a major league lineup. He went 0-for-3. Blanco was hitting .301 with an .883 on-base-plus-slugging percentage entering the game. ... Nationals OF Bryce Harper's home run Monday night was the first of his career against a pitcher younger than him, according to Elias. Harper hit his 37th homer of the season against Phillies rookie Aaron Nola. Harper (born Oct. 16, 1992) is 231 days older than Nola (born June 4, 1993).