The left-hander has been especially dominant lately, and he'll look to help Washington move closer to clinching the NL East on Thursday night when he faces the fading Philadelphia Phillies.Washington shut down Strasburg, who was 15-6 with a 3.16 ERA, when he reached a previously imposed innings limit after his start against Miami on Sept. 7.The playoff-bound Nationals (94-61), who reduced their magic number to clinch the East to four with an 8-4 win over Philadelphia on Wednesday, seem quite comfortable having Gonzalez be their ace the rest of the way.Gonzalez (20-8, 2.84 ERA) became the majors' first 20-game winner after allowing two unearned runs and three hits in seven innings of Saturday's 10-4 win over Milwaukee. He's 4-1 with a 0.79 ERA over his last five starts, giving up three earned runs in his last 34 innings."It doesn't feel like a 20th win for myself. It feels like a 20th win for the team," Gonzalez said. "This is a childhood dream, but at the same time, to do it with a team that's in first place makes it that much better."The Nationals have been in that position since May 22, largely due to the success of Gonzalez, who was acquired from Oakland for Tommy Milone and three others in the offseason. He's 2-1 with a 1.89 ERA while striking out 23 in three starts versus the Phillies, but he gave up three runs in six innings of a 4-2 defeat Aug. 25 in his most recent outing against them.Philadelphia (78-77), meanwhile, remained 5 1/2 games behind St. Louis for the NL's second wild card after Wednesday's loss. Jimmy Rollins homered for the Phillies, who are on the brink of being eliminated from contention after winning the East the past five seasons."We've been pushing real hard and it's catching up to us," manager Charlie Manuel said.The 19-year-old Bryce Harper became the second teen in major league history to reach 20 homers after hitting a two-run shot in the first and finished with three RBIs.Tony Conigliaro hit 24 for Boston in 1964."That's nothing new to me," manager Davey Johnson said. "I saw him hit a 500-foot homer when he was 14 years old. The thing is, he thinks he should be hitting .400."Harper will face fellow rookie Tyler Cloyd, who takes the mound for the Phillies after a stellar performance his last time out.Cloyd (2-1, 3.86) had the best outing of his short career, giving up one run and three hits while throwing only 88 pitches in eight innings of a 16-1 win over the New York Mets last Thursday. He had allowed seven runs in seven innings over his previous two starts.The right-hander went 15-1 between Double- and Triple-A and is making the most of his late-August call-up."I just came into the year just trying to go out and have a good year, go out and be strong every outing," Cloyd told the team's official website. "It happened, and everything just kind of fell the way it did."Washington had lost seven of the previous eight meetings with Philadelphia before Wednesday's victory.