The Mets' No. 2 prospect struck out 10, including Harper twice, over six innings for his first Triple-A win as the Buffalo Bisons defeated Syracuse, 6-4.
Harvey (1-1), gave up three runs on four hits and three walks and hit a batter. He made his 95th pitch of the night count, fanning Jeff Howell to end the sixth and strand a runner at second. The strikeouts matched the career high he established twice last season -- on May 27 with Class A Advanced St. Lucie and on July 28 with Double-A Binghamton.
"I was really keeping the fastball down, moving it well inside and outside," Harvey said. "I was able to throw the curve for strikes, which always helps. The biggest thing, I'd say, was getting ahead. Whether it was fastball or curveball, I was able to execute pretty well and I was able to expand as the at-bat went on."
Harvey picked up his first win in four starts for the Bisons. The Connecticut native entered the game with a 7.62 ERA and had allowed International League foes to hit .357 against him.
"I'm real happy," Harvey said. "It was good to get out there and help the team out and I was just trying to make my pitches and keep the game within winning distance. And I was able to do that."
Harvey held Harper, MLB.com's No. 2 prospect, hitless in three at-bats, fanning him twice. It was the second time the two have faced each other, with Harvey also besting Harper last July 28 in Harrisburg. For his part, the Mets' 2010 first-round pick has given little thought to facing the player drafted six spots ahead of him.
"I haven't really looked at it as a competition between me vs. him. It's baseball," Harvey said.
The University of North Carolina product credited bullpen sessions this week for the difference between his outing on Friday and his start on April 15, when he surrendered six runs on six hits over 3 2/3 innings against Pawtucket.
"The bullpen this week was about working both sides of the plate and keeping the fastball down," he said. "I was a little sporadic with it, I was leaving it up."
Harvey also contributed at the plate, going 2-for-3 with an RBI. Valentino Pascucci was 2-for-5 with a homer and two RBIs to extend his hitting streak to six games. Jordany Valdespin, the Mets' No. 9 prospect, also had two hits and scored a run.
Nationals No. 14 prospect Tyler Moore hit his sixth homer, a two-run shot, for the Chiefs, who have lost five straight.