Clements' play in the secondary has been exceptional.

Clements has been in the hip pocket of San Francisco receivers during team drills, giving the 49ers the kind of coverage ability the team covets to improve a defense that ranked 26th in the NFL last season.

"I'm just trying to make us better as a team as well as myself, just trying to go out there and compete and do everything that I can do to make my teammates better by pushing them, and vice versa, them pushing me as well," Clements said Wednesday.

The 49ers made considerable upgrades this offseason to both their secondary and wide receivers, and that has resulted in some spirited summer competition on a team that has playoff intentions after four consecutive losing seasons.

Clements has been right in the middle of it all, clamping onto his new teammates and making plays in coverage, almost to the frustration of receivers who can't get open against him.

One of the best daily battles of camp is Clements going man-to-man against Darrell Jackson, whom the 49ers acquired earlier this year in a draft-weekend trade. Jackson led the Seattle Seahawks in receptions four of the past six seasons and has moved in as San Francisco's starting split end and possible No. 1 receiver.

"He's a great corner, and anytime you go against cornerbacks like that, you're going to have your good battles in the NFL," Jackson said. "Nate knows what he's doing and he's very smart. I push him, he pushes me, and that's how we get each other better."

Clements combines with Walt Harris to give the 49ers potentially their best set of starting cornerbacks since Pro Bowlers Deion Sanders and Eric Davis were the starting corners for San Francisco's last Super Bowl team in 1994.

Harris was acquired in free agency last year to considerably less fanfare than Clements. But he emerged to have the finest season of his 11-year NFL career, leading the NFC with eight interceptions to earn Pro Bowl honors for the first time.

But the new top dog in the San Francisco secondary clearly is Clements, who is on the cusp of becoming one of the elite cornerbacks in the NFL as he enters the prime of his career.

"Nate's a good catch both on and off the field," 49ers coach Mike Nolan said. "It's rare that you get a guy in free agency that is as good an accomplished football player, but as well he's going to be even a leader. He's very confident but carries himself well, he works hard and he plays the complete game."

After playing his first six seasons in the relative NFL obscurity of Buffalo, Clements is ready to make his mark in a larger metropolis with a young team that is on the rise.

"I just bring it to practice every day and try to bring energy, just as well as in the games," Clements said. "We all have a common goal here. You ask any player on this team and the goal is to win. That's what we're here for, and that's why I'm here."