DENVER -- The Giants knew their season-opening trip to Denver would be like climbing a mountain.

	Sehorn

As it turned out, the trip was worse than expected. The Broncos drilled the Giants 31-20 by taking advantage of their cornerbacks. Jason Sehorn was inactive because of a knee injury. Coach Jim Fassel hoped that the defense could get by with veteran Dave Thomas and rookies William Peterson and Will Allen. They shied away from using veteran third-corner Emmanuel McDaniel in key situations.

Quarterback Brian Griese tore that secondary apart, completing 21 of 29 passes for 330 yards and three touchdowns. The most disturbing problem was that Thomas, a starter on last year's Super Bowl team, was beaten for two touchdowns. After Broncos receiver Rod Smith beat Thomas for a 28-yard touchdown, Fassel benched him.

The Giants finished the game with two rookies -- Peterson and Allen -- on the field.

"The bottom line is, in the first half, we just made too many mental mistakes with blown coverages," Fassel said. "One touchdown (a 1-yarder to an open Patrick Hape) had their tight end running open and our safety didn't take him. As a result, they threw a touchdown pass. Too many times, we had a guy well coverage, but they've got to keep their head up."

After the game, the Giants accepted the loss as a team loss.

"I can't single out anyone else when I made mistakes, too," linebacker Jessie Armstead said. "I shouldn't have made mistakes like I did tonight. I can't make any excuses. I'm paid to play no matter what the circumstances. You're trying to make something happen and you should just be doing your job. We weren't tired. We just got beat. We made mistakes: mental mistakes, simple things."

The Broncos burned the talented Giants defense for 473 yards on 65 plays. Not once was quarterback Brian Griese thrown down for a sack.

"They wore our defense down a bit although I don't think we ever got tired," Fassel said. "They are a good football team."

Perhaps the strangest site on the field was seeing Sehorn in street clothes but not on the Giants bench area. To be in the bench area, players or coaches have to wear Reebock clothing. Sehorn's a Nike guy. So he stood the entire game alone on the 25, not going over to help any of his young mates in the secondary.

Strange.

With Thomas benched and Sehorn's knee still a question mark, it's possible that the Giants may have to play next week's game against the Packers with the two rookies.

"Their next game is against Brett Favre," Broncos receiver Rod Smith said. "Good luck."

John Clayton is a senior NFL writer for ESPN.com.