Scherzer retired all 13 batters he faced, striking out seven, after replacing Gonzalez in the third inning of a 6-4 loss to Houston on Tuesday. He hit 98 mph on one fastball and was consistently at 96 mph.

"This is the start of what we believe will be big things for him," Diamondbacks manager Bob Melvin said.

"I'm excited to have the opportunity to go out and get wins for my team," said Scherzer, who dominated in four starts for Class AAA Tucson this season, going 0-0 with a 1.17 ERA and 38 strikeouts in 23 innings. "I like pitching the best. Whatever role, I'll do."

Scherzer, the Diamondbacks' first-round pick in the 2006 draft, signed a major league contract May 31, 2007, that guaranteed him $4.3 million and could max out at $5.75 million. He received a $3 million signing bonus.

Scherzer threw only a few sliders and changeups among his 43 pitches Tuesday, although the Diamondbacks like the way he has grown his repertoire, even since spring training. He struck out Houston shortstop Miguel Tejada on an 84 mph changeup after throwing him an inside fastball at 98 mph the pitch before.

"His breaking ball has a little better slope to it," Melvin said. "It has some bite to it. As a starter, he will have to throw his other pitches. But when push comes to shove, he does have that electric fastball."

Gonzalez, who has pitched out of the bullpen before in his five seasons with the Diamondbacks, was 4-0 as a reliever last season, 6-1 in his career.