The Dallas Cowboys' wakeup call came late again today, but this time it was answered by the defense.

Safeties Dextor Clinkscale and Michael Downs made touchdown returns in a 12-second span late in the fourth quarter and the Cowboys downed the New York Giants, 28-13, to stay undefeated.

Dallas, now the only NFL team with a 3-0 record, had to come from behind for the third consecutive week and, said Coach Tom Landry, "The defense won it for us. We gave them plenty of chances to beat us."

With New York working to overcome a 14-13 deficit, Larry Flowers intercepted a pass by Dallas' Danny White and the Giants set up at the Cowboys' 40. Three plays later, it was third and one and Scott Brunner tried to pass to running back Billy Campfield.

Blitzing linebacker Anthony Dickerson hit Brunner just as he threw and Clinkscale stepped in front of Campfield, intercepted at the 32 and ran 68 yards for his first professional touchdown with 6:17 to play.

On the next kickoff, Robert Newhouse jarred the ball from Campfield and Downs, fielding it at the 10-yard line, trotted in for six points.

Landry said turnovers by the offense gave the Giants numerous scoring chances, but "we had our best performance of the year from the defense. It was a hard-hitting game and we've got a lot of injuries."

Those included a leg injury to running back Tony Dorsett and a foot injury to wide receiver Tony Hill. Landry said he was not sure if either would be available next Sunday.

The Cowboys' physician, Marvin Knight, said Dorsett apparently strained the medial collateral ligament of his right knee, and that the seriousness of the injury could not be determined until Monday.

Dorsett said the knee "is either bruised or stretched, and I think it's more of a stretch than a bruise. As I left the field, it started to grab."

Doug Donley, subbing for Hill, caught six passes for 88 yards. In his two-year career entering the game, he had only caught five balls.

"It's the same old deal," White said. "I don't think I have to go over it again . . . It's a combination of not moving the ball and our defense not being able to stop them in a hurry."

Even so, Dallas took a 14-3 lead on two touchdowns in the last two minutes of the first half. Both came on short passes from White to tight end Doug Cosbie. The Giants rallied in the third quarter before losing their eighth straight in Texas Stadium.

Brunner completed a 28-yard pass to Butch Woolfolk, and on the next play, Woolfolk plunged a yard for the touchdown to make it 14-10. Brunner's 56-yard pass to Earnest Gray set up Ali Haji-Sheikh's second field goal, a 27-yarder.

Cosbie's first touchdown, from four yards, was hotly disputed.

Linebacker Lawrence Taylor stripped Cosbie of the ball just as he came down deep in the end zone, but field judge Bill Stanley ruled Cosbie had possession when his feet touched the ground.

Three plays later, Everson Walls picked off a pass by Brunner and ran 37 yards to the one-yard line.

After Dorsett lost a yard, White again threw for Cosbie, who had the ball brushed from his hands by cornerback Mark Haynes, fell to his knees, lost a shoe, reached out and grabbed the ball with his left hand.

Brunner walked off the field but never returned to the game after the hard hit by Dickerson.