PHOENIX (AP) -- Another shutout, another complete game and one awesome game-saving fastball.

	D-Backs catcher Damian Miller says Johnson is "seems to be getting better every single start."

"It's amazing, especially for a 36-year-old guy who seems to be getting better every single start," catcher Damian Miller said. "It's quite a run for him, and it's fun for me just to be a part of it."

Johnson (4-0) allowed four hits, struck out eight, walked three and even drove in a run with a single in the sixth inning. The Diamondbacks' other two runs came on a passed ball by catcher Ben Petrick and a wild pitch by Brian Bohanon.

Johnson is just one out short of having a complete game in all four starts. In 35 2/3 innings this season, he has struck out 42, walked five and allowed three earned runs. His ERA is 0.76.

Johnson pitched to 102 batters without a walk before Larry Walker drew a base on balls with one out in the fourth inning. Johnson had 39 strikeouts during that 29-inning span.

Johnson's control finally faltered in the eighth, when he gave up a single to Neifi Perez, then walked pinch-hitter Jeff Manto and Brian Hunter to load the bases with two outs. Then, on a 3-2 pitch with the crowd chanting "Randy, Randy," Johnson threw a 97 mph fastball that virtually exploded across the inside corner of the plate for strike three.

"The pitch to Lansing, the 3-2 unhittable pitch, you've got to be a star to make that pitch," Colorado manager Buddy Bell said, "and that's exactly what he is. That's why he's such a great pitcher."

Johnson thrust his fist into the air in triumph.

"Mechanic-wise I wasn't really on tonight," Johnson said. "Late in the game it kind of came back again and my concentration left me for a moment, and it could have been a situation where the game could have gotten out of hand very easily with Mike Lansing up there. Fortunately, I was able to throw a strike with a 3-2 count with the bases loaded. I don't think that's a situation any pitcher wants to be in."

If this is the best that Johnson has ever pitched early in a season, he doesn't want to talk about it.

"I try not to think about it," he said. "I try to stay focused and go out there and pitch as good as I can on a given day."

Johnson had five consecutive batters hit the ball for an out on the first pitch. That allowed him to throw a season-low 101 pitches. The seventh inning was his second three-pitch inning in as many games.

"To economize his pitches has been a real key for him over the last couple of outings," manager Buck Showalter said. "Tonight he picked his spots where he steps it up a little bit. He does have that extra gear."

Colorado starter Rolando Arrojo (1-2) left the game in the second inning with runners on first and second and no outs. He strained his left hamstring in the first inning, then bruised his left calf when he was hit by Travis Lee's line drive to lead off the second. He left after he couldn't come up with Miller's soft grounder.

Arizona, which won three out of four from the Rockies, scored an unearned run off Arrojo in the first when Jay Bell and Luis Gonzalez walked with one out. They advanced on Erubiel Durazo's groundout, then Bell scored on a passed ball.

Bohanon, who lost his job in the rotation after three horrible starts, didn't allow a run until he walked Steve Finley and Lee to start the sixth. The runners moved up on Miller's fly out to right, then Andy Fox was walked intentionally to load the bases for Johnson.

Bohanon's wild pitch to Johnson, which probably should have been ruled another passed ball by Petrick, allowed Finley to score, then Johnson singled up the middle. Lee scored, but Fox was thrown out at the plate by the center fielder Hunter.

Game notes
The Diamondbacks will activate closer Matt Mantei on Friday. He's been on the disabled list since April 2 with biceps tendinitis. ... Walker asked to be in the lineup because he's never started in three opportunities against Johnson and was livid over a Denver columnist's suggestion that he was afraid to face the big lefty. Walker was 0-for-3 with the walk. ... Until Todd Helton's one-out double in the second, left-handed batters were 0-for-13 against Johnson this season. ... Hunter is 0-for-15 lifetime against Johnson.