Gray, 23, the third overall pick in 2013 and MLB.com's No. 16 prospect heading into this season, topped out at 96 mph on his fastball and commanded his slider.
Gray threw strikes on 17 of his 23 pitches in two innings. Three other starter types -- the Rockies' Tyler Matzek and the Padres' Tyson Ross and Aaron Northcraft -- all needed 40 pitches, and only Northcraft lasted two innings. Gray also pitched with swagger and emotion.
"I'm trying to have controlled aggression, but when you get into a competitive game like that everything goes away and it's just competitiveness," Gray said. "It can't help but come out."
Gray twice touched 96 mph, once on a four-seam fastball to put away fourth-inning leadoff hitter Wil Myers and again on a ball to Matt Kemp. He had two sharp sliders to Wil Nieves -- the second he made Nieves chase to end the third with Alonso at third.
"Last year I didn't have [the slider] dialed in like I had in the past, but it's good to know I have it back," Gray said.
Rockies manager Walt Weiss said, "That cannot be an easy at-bat, especially for right-handed hitters."
It was a second straight impressive Cactus League outing for Gray, who spent last year -- his first full pro season -- at Double-A Tulsa (10-5, 3.91 ERA in 24 starts). Such work will have fans clamoring for him in the Majors sooner than later.
"It's too early," Weiss said. "He's obviously a talented kid. He looks the part. We just want to make sure whenever he does come up with us, he's ready to go."
• Rockies catcher Nick Hundley delivered a two-run double in the third in his first spring game against the Padres, for whom he played from 2008 until he was traded to the Orioles last May.
• Rockies non-roster lefty John Lannan fanned two and pitched around one hit and one walk in two scoreless innings. Lefty Chris Rusin gave up three hits and a walk but limited the damage to one run in two innings. Righty bullpen candidate Jorge Rondon hit 97 and 98 on consecutive fastballs and escaped the second by forcing a Jedd Gyorko grounder. Non-roster lefty Yohan Flande, who could start or pitch relief, forced a double-play grounder to end the game.
• Shortstop Charlie Culberson delivered an RBI single with runners at the corners in the second and made a diving play behind Gray. Culberson has shortstop tools and can be a key depth piece if he can hit to all fields and shake the issues that led to a .195 average last year. The run-scoring single off Northcraft went the opposite way.
Thomas Harding is a reporter for MLB.com. Read his blog, Hardball in the Rockies, follow him on Twitter @harding_at_mlb, and like his Facebook page, Thomas Harding and Friends at www.Rockies.com. This story was not subject to the approval of Major League Baseball or its clubs.