Backed by some solid pitching and enough offense, the Philadelphia Phillies can record their first road sweep of the Washington Nationals in seven years.

If Tanner Roark's early inconsistency continues for Washington, the Phillies might have a good chance to accomplish that feat Thursday.

A night after holding on for a 4-3 victory, Philadelphia (11-10) got seven innings of two-hit ball from Jeremy Hellickson and single-run innings from the sixth through eighth to win 3-0 on Wednesday. Winners in five of six, the overachieving Phillies are poised to sweep a set in Washington for the first time since May 2009.

"They're pretty tough right now," Nationals manager Dusty Baker said after his team was blanked for the first time.

Philadelphia has held the Nationals (14-6) to nine hits combined, two for extra bases, and struck out nine in each contest. Offensively, it's come through enough to prevail after being outscored 19-5 while dropping two of three to visiting Washington earlier this month.

''(Manager) Pete (Mackanin) has been preaching to us since Day 1 that he believes in us," Hellickson said. "We all believe in each other."

If his first four starts are any indication, it's possible the Phillies are catching Roark (2-2, 2.63 ERA) at the right time even though he's coming off one of the most dominant efforts of his career.

The right-hander has alternated losses and wins, posting a 6.30 ERA in the defeats but yielding a combined six hits and striking out 19 while throwing seven scoreless innings in each victory. A career-high 15 of those strikeouts came while Roark allowed two hits in Saturday's 2-0 win over Minnesota.

It was only the second time in 52 starts that he fanned at least 10.

''On a given day, anybody can be world beater," Washington pitching coach Mike Maddux said. "(It) was Tanner's day to do that. Just to have that special moment.''

Roark has hardly been special while going 1-4 with a 7.18 ERA as a starter against Philadelphia. He dropped his third straight to the Phillies after giving up career highs of eight runs, 12 hits and not striking out anybody in a career-low 3 1/3 innings of an 8-5 loss in June.

Maikel Franco and Odubel Herrera were a combined 5 for 7 against Roark last season. Herrera is batting .357 with nine runs scored and nine walks in the last eight games.

Aaron Nola (1-2, 4.50) hopes to be better than April 16 when he gave up a career-worst seven runs, seven hits and walked three in five innings of an 8-1 loss to Washington. The right-hander should at least have the confidence that he can improve on that effort after yielding a run, four hits and striking out seven in seven innings of a 5-2 victory at Milwaukee on Friday.

"After the last outing, I felt I really needed to command the baseball inside a lot more," said Nola, who has lasted seven innings in three of his four starts.

He will finally try to get the best of Bryce Harper, who is 5 for 7 with two homers against him.

After Harper homered in all three games at Philadelphia, the Phillies haven't allowed him to hurt them. He's walked five times and has one hit this week.