It was natural if he was impatient. Saquon Barkley has heard so much about what he can do for the Giants, what he can do in the NFL. And so, it was somewhat remarkable the first time he touched the ball in Thursday night’s preseason opener, he busted out for 39 yards and was especially pleased with one particular aspect of the highlight-reel play.

“The patience I had on that play was definitely my favorite thing about that,’’ Barkley said. “Everyone talks about the speed is different in the NFL, to still be able to see you got that burst, you can get to that line of scrimmage like that and create space. Got to find a way to even gain more yards on that play.’’

Head coach and play-caller Pat Shurmur wasted no time giving Giants fans what they wanted to see. The very first play in an otherwise tepid 20-10 loss to the Browns at MetLife Stadium was a handoff to Barkley, and with one quick burst the rookie running back showed what all the fuss is about.

What looked to be a modest gain up the middle turned into something much more, as Barkley used a sharp cut to elude cornerback Denzel Ward — one of three defenders to swing and miss — and then scooted to his right, sprinting up the sideline, stopped only when safety Damarious Randall pushed him out of bounds. The 39-yard eruption was the first and, by far, the best moment of the evening for the Giants.

“I loved his first run,’’ Shurmur said. “If only they all could be like that. You could see, it wasn’t too big for him.’’

Odell Beckham Jr. was in uniform but held out of this game, meaning his comeback from a fractured left ankle will have to wait. The other starters took the field and did not do much of anything, with Barkley’s long gain the exception. The Giants had only two longer runs all of last season — both by Orleans Darkwa.

“What I saw on that first carry, the offensive line did a great job of creating space and creating a hole,’’ Barkley said. “I was able to have patience and [tight end] Evan [Engram] did an unbelievable job of blocking on the backside, and I was able to burst through the hole, make a guy miss and get up field.’’

The one highlight was the only highlight for Barkley. His other four rushing attempts went for no gain, minus-2 yards, 3 yards and 3 yards. His five runs produced 43 yards. Barkley is a gifted pass-catcher but Eli Manning did not target him once, which will not be the case once the real games begin.

“For some reason I didn’t get nervous, I didn’t really even get anxious,’’ Barkley said of his first game. “It was kinda a weird feeling. They said it will probably hit me when the national anthem goes off but I got locked in so quick. I’ve been preparing for this moment my whole life.’’

Manning in two series was 4-of-7 for 26 yards, operating behind his starting offensive line. He did not throw the ball down the field and his last play was a sack, as linebacker Mychal Kendricks on a blitz dropped Manning for a 10-yard loss, with neither center Jon Halapio nor running back Jonathan Stewart laying a glove on Kendricks.

Barkley’s run led to an Aldrick Rosas 42-yard field goal, the only points produced by the starting offense in two series.

“After the first game you see a lot about things you need to improve on,’’ Manning said. “There’s things guys need to settle down and get comfortable with everything.’’

The new coaching staff was eager to see what Davis Webb, the No. 2 quarterback, could do in an actual game. Webb struggled, competing only 9-of-22 passes for 70 yards, often wild-high with his throws. It was a rough outing for the second-year player, who as a rookie did not get a single snap in a regular-season game.

“I was very antsy to start with,’’ Webb said. “Really excited — my first game in almost a year so I was pumped up. Missed a couple of throws by a foot, really. I missed quite a few throws that were close. At the same time I did a lot of good things, in the two-minute drive at the end I found a lot of completions. Did my best but there’s a lot to learn from.’’

Shurmur said Webb “gets a little amped up at times and that’s what causes the ball to sail a little bit, but he had his moments. He had some good plays in there.’’

Three takeaways