ARLINGTON, Texas – Drew Lock experienced a strange confluence of emotions on Thanksgiving.

The six-year NFL quarterback started his first game of the season in place of an injured Tommy DeVito. The competitor in Lock was unhappy the result of his milestone appearance was a 27-20 loss to the Dallas Cowboys in AT&T Stadium. But the part of Lock that is an athlete and football player? He relished the opportunity to play.

"You're upset when you lose, but nothing but fun," Lock said. "You love football. You love being able to come out here and play on Thanksgiving. You want to win. Upset we didn't. There were a couple of things we could have done better. But the last 24 hours, I won't forget it. Awesome opportunity to come out here and play. I wish we could have got it done. But I was very excited to be told I was playing and come out here to try to get a win."

Lock's performance was as diverse as his feelings.

He completed 65.6% of his passes for 178 yards but did not throw for a touchdown and his only interception was returned for a touchdown. Lock led the Giants with 57 rushing yards, 25 more than rookie running back Tyrone Tracy. The QB scored one of the Giants' touchdowns on an 8-yard run in the fourth quarter and set up Tracy's touchdown with a 28-yard scramble that was originally ruled a score. That was overturned on replay and Tracy scored on the next snap. Lock also lost a fumble on the first series of the third quarter.

"I thought Drew did some good stuff, but two big turnovers," coach Brian Daboll said. "One on a screen we had a big opportunity to get a big play on, and then coming out in the second half, up in the pocket and getting the ball knocked out. You can't have those turnovers."

It's been a whirlwind couple of weeks for both Lock and DeVito. The drama began on Nov. 18 when the Giants returned from their bye week and Daboll announced that DeVito, who had been the No. 3 quarterback all season, had leapfrogged Lock and replaced Daniel Jones as the starter. DeVito played the entire game last Sunday vs. Tampa Bay but came away with a sore throwing forearm. That sharply limited his participation in walk-throughs as the Giants prepared for a short-week road game.

On Wednesday, DeVito stayed behind to undergo further examination while the Giants flew to Texas. He eventually joined the team but was inactive as the third quarterback in the game.

"If it was a Sunday, I think I would have been able to play," DeVito said.

"(Wednesday), he came in, he was probably a little bit more sore than he was the day before," Daboll said. "A little bit swollen. We wanted to make sure that everything was alright. Went to get it tested and in the morning, even before he went to get looked at, we knew that he probably wouldn't be able to do it (face the Cowboys)."

When did Lock learn he would start?

"I think before we left, I was told it was looking that way," he said. "Then by the time Tommy got here, we knew for sure."

Lock took the field without ever having a full practice with the rest of the starters.

Tracy's touchdown, sandwiched between two Brandon Aubrey field goals, gave the Giants their first lead since Oct. 6 in Seattle. Then disaster struck on the Giants' first after Aubrey's 33-yarder. Lock tried to throw a screen pass to Devin Singletary. But linebacker DeMarvion Overshown batted the ball in the air, caught it, and returned it 23 yards for the touchdown that gave Dallas the lead for good at 13-7.

"(Overshown) walked up on the ball pre-snap," Lock said. "I knew it was going to happen. I faked it, came back, got the bump from the back, I thought I had enough to squeeze it in there. (Overshown) made a good play. He got his hand on it, tipped it up and took it back."

Graham Gano's 46-yard field goal closed the Giants' deficit to 13-10 at halftime. But another critical sequence early in the third quarter put Dallas back in command.

On the third play of the half, Lock was sacked for a 2-yard loss by Eric Kendricks and fumbled. The ball was recovered at the Giants' 38-yard line by – who else? – Overshown.

KaVontae Turpin caught a short Cooper Rush pass and stretched it into a 30-yard gain to the eight. Two plays later, Rush was hit by Bobby Okereke as he scrambled and fumbled. Micah McFadden pounced on the ball in the end zone to seemingly end Dallas' threat. But a replay review reversed the call because Rush was already down by contact when he lost the ball. On the next play, Rush threw a 2-yard touchdown pass to Brandin Cooks. Rico Dowdle scored on a 4-yard run seven minutes later to make it 27-10 and end most of the mystery about the outcome.

It might have been different had the fumble stood.

"Big bang call, heads up play by him diving, getting his knee down," Okereke said. "But I knew it was close. He was going to dive for the end zone, so I just wanted to punch the ball out. (They) made the call they deemed was fit. There's not a lot of room in this game to feel sorry for yourselves."

The Giants scored 10 fourth-quarter points to narrow the final margin, but many of the postgame questions focused on who will play quarterback when the Giants return to action on Dec. 8 against New Orleans in MetLife Stadium.

Daboll said DeVito will "probably" he ready but wasn't prepared to anoint either he or Lock immediately after the game.

DeVito said his exam showed no structural damage and he plans to return to action but doesn't know if he'll start.

Lock, meanwhile, was not looking that far ahead. He was still exulting in the opportunity to play and hoped to squeeze as much as possible from it. Because of that, Lock didn't directly answer a question about whether he thinks he did enough in the game to remain the starter.

"I'm not thinking about that right now," he said. "I'm going to leave here, get on the plane and watch tape to see what I could have done better. Learn from it. Grow. If the opportunity comes again, then be ready to play and play better than we did today."

*The Giants' defensive line had a rough afternoon as Dexter Lawrence, Rakeem Nunez-Roches and D.J. Davidson all left with injuries.

Lawrence, who leads the team with 9.0 sacks, hurt his left elbow, which was in a brace after the game. He will undergo an MRI.

"I over-extended (it) and Bobby (Okereke) came down and hit it real hard and it popped out of place," Lawrence said. "They popped it back in. They didn't see anything on the X-ray that was concerning. I'm in pain, but I still have strength, so they're hopeful (he will soon return)."

Nunez-Roches suffered a stinger and Davidson injured his shoulder. That left the Giants with two healthy linemen late in the game, Jordon Riley and Elijah Chatman.