ARLINGTON, Texas — No one was expecting anything great or even very good out of Drew Lock in his first start for the Giants. What he needed to do, most of all, is not do what he has done far too often in his previous starting ᴀssignments, when he was with the Broncos and Seahawks.

Lock had to avoid the big mistake. And he could not do it at a key moment in the second quarter of the Giants’ 27-20 Thanksgiving loss to the Cowboys at AT&T Stadium.

Lock on the first offensive series scrambled for 28 yards to set up Tyrone Tracy’s 1-yard touchdown to put the Giants ahead 7-3. They had a 7-6 lead and were feeling relatively good about themselves coming out for their second possession. It did not last long and did not go well and just like that, the lead was a deficit.

On first down, the Giants were setting up a screen pᴀss to Devin Singletary.

Linebacker DeMarvion Overshown stormed in and nearly overpowered Singletary, knocking the 203-pound running back backward a step.

Singletary then tried to escape and get free and Lock needed to wait a split second and then lob the ball over Overshown.

Instead, Lock tossed a flat pᴀss that Overshown deflected with his arm, into the air and into his own hands for an interception. It was off to the races from there on a 23-yard pick-six that gave the Cowboys a 13-7 lead early in the second quarter.

Head coach Brian Daboll thought it could have been a big gain for the Giants.

“Yeah, he thought he could get around him rather than layer over the top,’’ Daboll said. “There was really nobody else out there. The guy who was covered, his man, the guy made a nice play.’’

Lock said “Ugh’’ when asked about that play.

“It was classic,’’ he said. “I thought I had enough to squeeze it in there. He made a good play. He got his hand on it, tipped it up and took it back.

“Looking back at it now that that happened, just go ahead and dirt it. I could get it over the top. Then you run the risk when you do float it — because you’ve got to wait a little when the back chips when you do float it, offensive lineman downfield starts to come into play on the screen. … Yeah, float it or put it at his feet.”

Early in the third quarter, Lock scrambled and lost the ball on a fumble.

This is often what you get with Lock, who amᴀsses turnovers as if he worked in a bakery.

He came to the Giants on a one-year deal for $5 million with a track record as something of a gunslinger — and not in a good way.

He had 28 touchdown pᴀsses and 23 interceptions and that is a terrible ratio for a quarterback.

In his “best” season, he threw 16 touchdown pᴀsses and 15 interceptions for the Broncos in 2020. He has a reputation of taking and giving with equal frequency.

“I thought Drew did some good stuff,’’ Daboll said, “but, you know, two big turnovers. You can’t have those turnovers.”