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DENVER -- Champ Bailey figured the last play was his to make.

Why not? Tony Romo had been testing him all afternoon, even though he kept acing every exam.

"I welcome it. Please do. That's the only way I get a chance to make plays," said Bailey, who had eight tackles, broke up four passes and made one key interception in Denver's 17-10 win over Dallas on Sunday.

His biggest play came with a second left when he knocked away the potential tying touchdown pass from Romo to Sam Hurd on fourth-and-goal from the 2.

With the blitz coming, Romo quickly fired toward Hurd cutting across the middle. Bailey reached around and swatted the pass away with his left hand at the last second, giving the Broncos their first 4-0 start since 2003.

"Maybe they thought they could catch Champ sleeping," teammate D.J. Williams surmised. "One of the top corners in the league, my last play, I wouldn't go toward him."

Romo would. Again.

"They're good all over," Romo insisted of Denver's top-ranked defense. "I understand Champ's good. It's questionable. I think you could go either way on that call. It's a bang-bang play and the corner's always driving on the ball. If he gets to the ball early, that's part of the game. ... Those are always going to be contested throws."

The Broncos had taken the lead on Brandon Marshall's 51-yard touchdown catch from Kyle Orton with 1:46 remaining, providing some vindication for the Pro Bowl receiver whose temper tantrum during training camp earned him a nine-day suspension from coach Josh McDaniels.

By the look of their emotional embrace on the sideline after he zigzagged his way into the end zone, Marshall and McDaniels have reconciled.

On the other sideline, Cowboys owner Jerry Jones, coach Wade Phillips and cornerback Terence Newman were swearing a flag should have been thrown on Marshall for offensive pass interference.

"I couldn't have played that play any better," Newman said. "I could have sworn it was going to be a penalty. He grabbed my jersey and threw me to the side. If that wasn't a hold, I don't know what is. I tried to grab him back. I figured either way, we were both going to be called for holding. But the refs didn't see it."

Marshall grabbed the ball off the top of Newman's helmet at the 25-yard line, then avoided three more tacklers on his way for the score.

Even then, Marshall was nervous.

"Going back to Pop Warner I've made a bunch of plays like that really didn't mean anything because we end up losing the game," Marshall said. "We knew their 2-minute offense is one of the best in the business."

Sure enough, Romo, ineffective in the second half when the Cowboys' first five drives ended in four punts and an interception by Bailey, found Hurd for a 53-yard gain on fourth-and-3 to the Broncos 20-yard line with a minute left.

The Cowboys reached the 2 with 9 seconds left. Romo spiked the ball on second-and-goal, then Bailey knocked away a high pass intended for Hurd before swatting away the last one that was right on the money.

"That surprised me," Broncos safety Brian Dawkins said. "Both times that surprised me. To challenge a Hall of Famer, still doing what he does? You saw what he did on that beautiful pick on the sideline. So that surprised me that they continued to go at Champ. I'm glad they did."

Bailey, who picked off a pass from Romo at his 6 in the third quarter, wasn't surprised Romo would test him one final time because the blitz was designed to coerce a quick pass to his man.

"If you want to keep testing me, putting the pressure on me, I'm with you," Bailey said.

Denver held the league's best rushing attack to just 74 yards on 25 carries, a 3-yard clip.

In the second half, Romo was 11 for 24 for 201 yards, no touchdowns and one interception.

"It happens, it happens," Dallas receiver Roy Williams said. "Michael Jordan scores nine points. Tiger can't come back on the final day. It happens. It happens."

Especially when Elvis Dumervil is breathing down his neck all game.

Romo was sacked five times, twice by Dumervil, who has eight in his last three games.

Denver's defenders filed into the locker room afterward crowing about having proved the critics wrong for blasting them this offseason and then dismissing their 3-0 start against bad offenses.

"To come out and do it against a great team shows we are great," D.J. Williams proclaimed.

Game notes

Orton improved to 17-2 at home as a starter since joining the league in 2005. ... Broncos RB Correll Buckhalter sprained his left ankle after gaining 55 yards on five receptions and 37 yards on six carries. He walked out of the stadium on crutches.