After rifling a slant to fellow rookie Antonio Callaway — who shed Giants cornerback Leonard Johnson for a 54-yard touchdown in the fourth quarter Thursday night — Baker Mayfield took off sprinting to the end zone to celebrate with his wide receiver.

There are no Heisman Trophies for him to win in the NFL, but Mayfield’s NFL preseason debut in a 20-10 win over the Giants offered hope for the woebegone Browns and undoubtedly thrilled the HBO “Hard Knocks” people.

The controversial No. 1-overall pick of the NFL draft earlier scrambled twice for first downs on a drive that culminated with a 10-yard TD pass to TE David Njoku. He appeared in command, having the kind of fun he used to have at Oklahoma, flashing the swagger and presence that endeared him to Browns general manager John Dorsey, from the moment he relieved starter Tyrod Taylor with 1:31 left in the first quarter.

In short, he looked more like Drew Brees than Johnny Manziel.

Mayfield was 11-of-20 for 212 yards and two TDs and finished with a 125.4 rating. He was also 3-of-13 rushing.

One drive ended when defensive tackle Robert Thomas rag-dolled Mayfield for an 11-yard sack.

“I had to get him down,” Thomas said. Asked what was running through his head on the play, Thomas said: “It’s so many rules with that now that I knew I couldn’t fall on top of him. My best bet was to just grab him, kinda throw him out of the way. That was just quick thinking out there [laugh].”

Thomas was nevertheless impressed with Mayfield.

“One thing I liked about the kid, he has great composure,” he said. “As a young guy, they usually get kinda frustrated, like you could kinda see when things aren’t going his way,” Thomas said. “He rolled with everything that was happening out there.”

Taylor (5-of-5, 99 yards, 1 TD) has been a godsend for the Browns and isn’t ready to be anybody’s bridge quarterback. But you can bet that Mayfield will be nipping at his heels at every turn.

Mayfield sounded as if he had been there before.

“Did some things well, but there’s definitely room for improvement,” he said. “I think a little bit of once those first-stringers came out, you could tell in and out of the huddle that there were some substitution problems. So, stuff like that needs to get ironed out, which is good to see.

“It’s good to get it out there early to where you can work on that and make sure it doesn’t happen again and then I’m happy with where we progressed, you know we got into a little rhythm. Obviously, you need to be able to run the ball better, but our guys for the first game were not too bad.”