OAKLAND (AP) — Sean Lee made an immediate impact in his return to the field for the Dallas Cowboys defense.

Lee’s sack on the opening drive forced a turnover that led to a Dallas score before special teams blunders doomed the Cowboys in a 19-17 preseason loss to the Oakland Raiders on Friday night.

“He’s just around the football a lot,” coach Jason Garrett said. “He’s a very instinctive guy. He studies so hard, but I just think he has a feel and a nose for the football. He’s always around it, he’s always making tackles.”

Lee flattened Matt Flynn on a delayed blitz for a sack fumble in his first game back from a toe injury that sidelined him for the final 10 games a year ago.

The Cowboys are counting on Lee’s return to help a revamped defense under new coordinator Monte Kiffin rebound from a disappointing end to the 2012 season.

Kiffin switched Dallas from a three-man front to a four-man line with star pass rusher DeMarcus Ware moving from stand-up linebacker to rush end. Ware’s presence helped lead to Lee’s big play.

“I came on a blitz, came free and I saw the quarterback and was able to get a good hit on him,” Lee said.

“That’s nice, not playing for a while and having a nice free hit on the quarterback. With DeMarcus he’s a guy you can stick him in on that and he kind of takes a couples guys with him. So it was nice to come free and get a hit like that.”

After forcing just 16 turnovers under fired coordinator Rob Ryan last year, the Cowboys have been very opportunistic so far this preseason by forcing four turnovers in the first two games, including rookie J.J. Wilcox’s end zone interception against Terrelle Pryor.

But the Raiders got a 30-yard touchdown pass from undrafted rookie Matt McGloin to fellow rookie Brice Butler and a go-ahead field goal from Eddy Carmona in the fourth quarter after B.W. Webb fumbled a punt at his 9.

It was a rough night for Dallas’ special teams as the Cowboys had a field goal blocked and allowed a 51-yard kickoff return.

“Those are plays that are going to hurt you,” Garrett said. “Those aren’t winning football plays. We got to make sure we correct that.”

Tony Romo, who sat out last week against Miami after offseason surgery to remove a cyst from his back, completed 6 of 8 passes for 88 yards in his first two series of the preseason.

Kyle Orton threw a 15-yard touchdown pass to Cole Beasley and rookie Joseph Randle scored on a 1-yard run in the fourth quarter for Dallas.

Flynn’s tenure in Oakland got off to a rough start when he was sacked by an unblocked Lee on his first drive, leading to a fumble that Jason Hatcher recovered for Dallas at the Raiders 16.

After a holding penalty, a tipped pass and a sack by rookie Sio Moore on Romo’s first drive of the preseason, the Cowboys were lucky to get a field goal out of that gift field position when Dan Bailey connected from 38 yards.

Both quarterbacks fared far better on their second drives with Flynn converting a pair of third downs on passes to Denarius Moore and Rod Streater to set up a 51-yard field goal by Sebastian Janikowski.

Romo completed 5 of 6 passes for 77 yards before Bailey’s field goal attempt was blocked by Tyvon Branch.

Flynn’s night was over after going 4 for 5 for 37 yards.

“We’re making strides,” Flynn said. “We still have a lot of work to do. I think that timing, that trust factor is coming. There are definitely things we need to clean up. My job is to get the ball in the hands of the playmakers.”

Pryor came in and mixed in some electrifying plays with questionable ones. Pryor ran 13 yards on a read option on his first play, delighting the fans who have been partial to the former Ohio State star since he joined the Raiders in the supplemental draft two years ago.

Pryor also showed poise in the pocket, throwing an 18-yard screen to Jamize Olawale and converting a third-and-8 with a 9-yard pass to Andre Holmes.

But those promising plays were erased when he rolled out on third-and-4 from the 6 and threw late across his body when he had room to run and was intercepted by Wilcox in the end zone.

“It was just me being greedy,” Pryor said. “I looked at the pictures and I could have ran it easy. That was just me being greedy.”

Pryor bounced back after Orton completed all six passes on an 80-yard touchdown drive and completed three passes for 54 yards in the final minute to set up a field goal by Janikowski.

“He’s really a dual threat,” Raiders coach Dennis Allen said. “He can run the football and I thought he threw the ball pretty well at times tonight. That’s one of the things we want to try to use, that skill set, and hopefully it will be another dimension to our offense.”

NOTES: Beasley left the game in the second half with a foot injury. X-rays were negative. ... Raiders RB Darren McFadden had three carries for 5 yards and caught an 8-yard pass in his brief appearance.