Matt Harvey wore sleeves only to the elbow on a 44-degree night at Citi Field, but he didn’t merely dress the part of tough guy. He was every bit Clint Eastwood last night, daring the Padres to make his day.

In the end, the Mets right-hander made manager Terry Collins’ day. Harvey’s 2013 debut was a beauty, giving the handful of fans in the ballpark a reason to celebrate the fact they showed up.

“It was one of those things I knew I was going to have to block out,” Harvey said, referring to the weather, after his one-hitter over seven shutout innings with 10 strikeouts led an 8-4 victory over the Padres. “It was cold for everybody.”

Lucas Duda, John Buck and Ike Davis all homered for the Mets, who have scored 19 runs in their first two games.

Everth Cabrera’s single leading off the fourth was the Padres’ only hit against Harvey, who closed his performance by retiring 10 of the final 11 batters he faced. Cabrera was picked off first base by Harvey, who didn’t allow a runner to reach second.

Harvey said a new pickoff move was among his offseason improvements.

“I attribute that to Ike, he kind of made fun of me for having a real bad pickoff move,” Harvey said. “So I definitely wanted to make it quicker and it’s something we worked on in spring training, and hopefully Ike won’t be saying that anymore.”

Harvey, who walked two, was finished after 94 pitches. The double-digit strikeout game was his third in 11 career starts. Harvey (1-0) received his first career Citi Field victory after going 0-2 with a 1.88 ERA in four starts here last season.

“He’s a little different than he was last fall,” Collins said. “Last fall he wanted to show everybody his stuff was plus stuff, which we had all heard, but he’s becoming a pitcher.”

Buck said he knew right from the start it could be a special game for Harvey, who struck out four in the first two innings.

“Overall his stuff is electric,” Buck said. “He was getting a lot of swings and misses late in counts with that elevated fastball.”