Harvey dominated the Twins, as they did not get a hit until Justin Morneau homered with two outs in the seventh inning of a 4-2 loss to New York.
Harvey, making his 13th career start, came just seven outs away from only the second no-hitter in Mets history before Morneau crushed a 2-2 slider off the foul pole in right field.
"It was a tough day offensively made tough by the guy on the other side," Twins manager Ron Gardenhire said. "I think we all saw that Harvey was throwing the baseball pretty well. He was throwing all of his pitches with a great fastball, a great changeup and a great slider. He pretty much held us in check."
Before Morneau's solo shot, the Twins had reached base just twice -- on walks from Ryan Doumit in the second inning and Josh Willingham in the fourth. Harvey simply overpowered the Twins with a fastball that reached 96 mph, and he struck out six.
He tried to get Morneau on an inside slider, but it was one of the few times it did not work out for the young right-hander.
"It was a good pitch -- he just put a good swing on it," Harvey said. "I think we'd gone in there three or four times with the slider, and you know, looking back we probably should have gone with another changeup or a fastball, but I made a good pitch, and he put a good swing on it."
Harvey ended up going a career-high eight innings and surrendering just two hits, as he also gave up a two-out single on a 3-2 fastball to Brian Dozier in the eighth.
"Going into it we knew he was throwing the ball really well," Dozier said. "Our mentality was to attack early. I knew from facing him in the Minor Leagues he comes at you with his fastball, but he had all three pitches working today."
He fared better than Diamond, who was making his season debut and gave up four runs on eight hits over 4 1/3 innings to get the loss.
Diamond was cruising until the fifth inning, when the Mets strung together six straight hits against him to chase him from the game. Marlon Byrd started it off with a solo blast before Ike Davis singled and was thrown out at second by left fielder Josh Willingham.
Justin Turner, Ruben Tejada, Collin Gowgill and Daniel Murphy then provided four straight hits before reliever Josh Roenicke came in to replace Diamond. Roenicke promptly gave up an RBI single to David Wright but was able to get out of the jam. It marked the first time the Mets had seven straight hits since doing it against the Astros on Aug. 1, 2001.
"I was hoping for better," Diamond said. "The way the first four innings went and the way I was able to get out of the third inning, I was pretty pumped by that. It was a big step, but the way the fifth sped up on me and the way they piled up hits on me was frustrating."
Willingham scored Joe Mauer with an RBI double in the ninth off closer Bobby Parnell, but Minnesota ended the game with its fifth loss in a row after starting the season with series wins over the Tigers and Orioles.
"They have another guy coming in there in Parnell throwing 96 mph, so he's not going to make it easy on you either with a great breaking ball," Gardenhire said. "So it's a tough day offensively when you're facing those types of arms. We had a little bit of an opportunity there, but they made the pitches there at the end when they needed to."