SAN DIEGO - The best team in baseball just got better.

The Diamondbacks took another big step forward Friday as Randy Johnson neared domination in a town that always seems to bring out his best.

Johnson gave up three hits and a run in six innings, striking out seven, and the most encouraging sign for the D-Backs in their 5-1 victory over San Diego at Petco Park was the way he did it.

Johnson was able to locate his fastball on the inside portion of the plate, a pitch that makes his slider that much more of a weapon. He got four of his seven strikeouts on sliders, including his two biggest when the Padres scored once and left the bases loaded in the fourth inning.

"He was dealing," catcher Miguel Montero said.

"This is the reason I'm playing. I feel I can do these kind of games," Johnson said.

Johnson, 1-1 after his 285th career victory, hit 96 mph once and 95 mph once on the stadium radar run while throwing 94 pitches in his third start of the season.

He did not give up a hit until the fourth inning, and his progression appears slightly ahead of where it was last year, when he did not record his first victory until his fifth start, before a later stretch in which he was 4-0 with 42 strikeouts and four walks in 29 2/3 innings.

"This was a step in the right direction," Johnson said. "It resembles a lot of last year, where the first couple of regular-season games for me were not great but then my third game was the game that would lead into my short stint of some quality games."

The D-Backs will showcase their major league-best 17-6 record on Fox today while attempting to rack up another series victory in their 22-game stretch against the NL West.

The D-Backs, 16-4 in the division, have won six series and split one entering their three-game set against the Padres.

They entered Friday with the best ERA in the majors, 3.09, and Johnson and the bullpen dropped it further.

"Once he got going, his confidence began to elevate," manager Bob Melvin said. "He pounded the inside part of the strike zone with his fastball. The velocity picked up considerably. We wanted to be patient with him, because we saw last year it took him a little while to get going."

Mark Reynolds hit a two-out, three-run home run to cap a five-run second inning for a 5-0 lead, and Johnson had only one strenuous inning, the fourth, when Kevin Kouzmanoff singled to center field to break up a no-hitter with one out and Khalil Greene doubled into the left-field corner.

Justin Huber, who hit his first major league homer off Johnson last Sunday, was struck in the left elbow on a 1-0 pitch to load the bases.

Johnson, 15-4 in his career against the Padres, threw two fastballs past Josh Bard to get ahead in the count. At 3-2, he threw a back-door slider that froze Bard for the strikeout.

Callix Crabbe singled to left field to drive in a run, making it 5-1, before San Diego manager Bud Black brought in Tony Clark to bat for Randy Wolf. Johnson struck Clark out on a 1-2 slider that dove down and in.

"That inning could have been a lot like last week," said Johnson, who gave up five runs in the sixth inning of a 9-4 loss to San Diego on Sunday.

"To just give up the one run was huge."