Clements drew such an assignment Sunday against the Dallas Cowboys, but the results were something shy of satisfactory in the 49ers' 35-22 loss on Sunday in Texas Stadium.

Cowboys wide receiver Terrell Owens, matched primarily against Clements' "off" coverage, had the second-most receiving yards of his career with seven catches for 213 yards and a touchdown. Yet, 49ers interim coach Mike Singletary said this was an assignment that Clements was fully capable of winning.

It was a disappointing performance for Clements, who generally is assigned the opposition's top receiver. That is the kind of responsibility given to the man who signed a seven-year, $64 million contract on the first day of 2007 free agency.

"Nate can cover 'T.O.' but he didn't do that today," Singletary said. "He is better than what he played today. I will not say Nate can't cover that guy. He can cover that guy all over the field. Nate is a man and a professional. He will recover and bounce back from today."

Clements admitted all of Owens' big plays came when he gave Owens a cushion at the line of scrimmage. But he said the play call often dictated that he not play bump-and-run coverage.

"I gave up a couple big plays," Clements said. "He got off today. I'm not taking anything away from him. I have confidence in what I can do against anybody. I'm going to make the corrections, and I'm going to be back at it. ... My mindset is I'm down overall, how the season's gone. I'm frustrated. But I'm confident in my abilities and in myself and my teammates."