Williams stifled San Diego over seven innings and the Phillies beat the Padres 5-3 on Sunday to complete a three-game sweep.
"It's going really well right now," Williams said. "We just want to keep it going.
The Phillies notched their 16th win in 21 games, the majors' best mark since the All-Star break.
Williams (4-8) entered the game with an 0-6 road record this season before dominating the fading Padres. He was charged with one run and five hits and struck out three.
"I just kept the ball down in the zone," Williams said. "If I consciously keep the ball down I get my ground balls. Then if I do throw one up in the zone I have them so conscious of looking down they miss the pitch."
Ken Giles worked the ninth to collect his sixth save in nine chances.
"That is the best we've seen Jerome all year," Phillies interim manager Pete Mackanin said. "He kept the ball down in the zone.
"He did a real nice job. I'm very happy about that."
There weren't many smiles in the other clubhouse. The Padres matched their season-high with their sixth straight loss and they have dropped seven of eight.
Andrew Cashner (4-12) worked 6 1-3 innings and allowed three runs and eight hits. He struck out four.
"Overall, I was throwing my fastball well and I was pretty pleased with my stuff today," Cashner said.
Chase Utley added a two-run, pinch-hit double in the eighth.
"That's the thing that has been happening to us for a while now," Mackanin said. "We just don't have that one opportunity to make something happen. It seems another one always pops up and we have been taking advantage of one or the other, or both, so that's been the difference."
Yangervis Solarte had an RBI single in the eighth to make it 5-2.
Justin Upton's two-out homer in the sixth cut the Phillies' lead to 2-1.
Odubel Herrera gave the Phillies a 2-0 lead when he hit his sixth homer of the season to open the sixth inning. Before Herrera's blast, Cashner had retired 14 of the previous 15 batters.
"We didn't execute three or four pitches, here and there, but you're going to do that throughout the course of a game," Padres interim manager Pat Murphy said. "It's just that they made us pay."
Williams gave the Phillies' unlikely second-half surge more life. He breezed through the first four innings, restricting the Padres to two baserunners.
The Phillies went ahead 1-0 in the first on Howard's RBI double. Hernandez and Herrrea singled and Howard smoked a line drive to right field that a diving Matt Kemp just missed to score Hernandez. With two runners in scoring position, Cashner escaped further damage by striking out Jeff Francoeur and getting Cody Asche to fly out.
The Phillies headed for Arizona to open a three-game series riding a significant wave of momentum.
"Everybody is coming to play and doing the best job they can," Hernandez said.
Which has Mackanin grinning.
"This is fun," he said.
Padres: OF Wil Myers (left wrist) swung a short bat in his rehabilitation process on Sunday. His next step is hitting off the tee and soft toss pitches.
Phillies: RHP Aaron Harang (5-12, 4.11) will open the Arizona series on Monday. Harang, who has lost nine of his last 10 decisions, is 4-9 lifetime against the Diamondbacks.
Padres: RHP Ian Kennedy (6-10, 4.49) goes for his fourth win in his last five starts as the Padres open a three-game series on Monday at home with Cincinnati.
SAME TEAM, DIFFERENT SITE
Williams is familiar with the Padres' haunts. He's one of 12 active pitchers to have toed the rubber at Petco Park and Qualcomm Stadium. The Padres moved into Petco Park in 2004.