RENTON, Wash. (AP) - It's not rookie Lawrence Jackson's speed off the corner, or his ability to adapt to playing a couple of positions for the Seattle Seahawks that impresses Pro Bowler Patrick Kerney the most.

It's Jackson's mind. Namely, his thought process.

"This is going to sound weird, but I like his mind-set the most," Kerney said Tuesday. "He has a very open mind to learning. He's very intelligent and that's something that is rarely talked about with pass rushers in this league."

Jackson's talent is also creating a bit of a log jam at defensive end, opposite Kerney.

With Kerney returning to practice on Monday, fully recovered from a strained calf that bothered him in the early stages of training camp, the focus on Seattle's defensive line now has turned to the competition between Jackson and Darryl Tapp for the other defensive end spot.

Jackson will get the nod for the second consecutive week next Monday night when Seattle plays its third preseason game, at San Diego.

"We're looking for him to do even more. He did some good, natural things in the pass rush. But now we want to see him sack the passer. Things like that," Seattle defensive coordinator John Marshall said of Jackson's performance against Chicago last Saturday. "But he's come a long ways; he really has. Now we've got to give him the opportunity to raise his level of production."

Seattle drafted Jackson because of his smarts and his versatility. He has the speed and technique to take on offensive linemen coming off the corner, but also showed an ability at USC to play defensive tackles and be a rusher up the middle in passing situations.

While his physical talents have impressed many during training camp, it's Jackson's smarts that caught the attention of his mentor.

"Rushing the passer, it's a chess game. If you can't think, if you're just a tall, fast, strong guy, you're not going to get to the quarterback," Kerney said. "There's a chess game to it, so much that goes into it, and Lawrence has that, I think."

But Jackson's rise leaves a question about what exactly Tapp's role will be when the season begins. Tapp started all 16 games last season, but has always been considered undersized for his position at just 6-foot-1 and 270 pounds. Jackson is 6-4.

Asked what role he expects to have this season, Tapp said: "We'll find out together."

Jackson is trying to stay clear of the talk surrounding the competition between himself and Tapp. Much like the rest of the league, Seattle has rotated many of its defensive linemen in recent seasons, trying to keep them fresh. That means it's likely both Jackson and Tapp will see significant time on the field. Where it might have an impact is with reserves like Baraka Atkins and Jason Babin.

"That's something I don't have any control of. I come out here and it's my job to get better as a football player to help the Seahawks," Jackson said. "It's not my job to worry about Darryl or whatever is going on with that. After you guys bring it up I don't even think about it anymore."

Notes: QB Matt Hasselbeck left Tuesday morning's practice after about 45 minutes when his back began to tighten up. He returned at the start of the afternoon session to do some stretching with the team, but walked off the field and back into the locker room with the rest of the injured Seahawks. The Pro Bowl quarterback fully participated in a practice Monday for the first time since his back stiffened following Seattle's first preseason game against Minnesota on Aug. 8. The Seahawks won 34-17. ... Tuesday was Seattle's last full day of two-a-days. The Seahawks will have a full practice Wednesday morning, followed by a special teams practice in the afternoon, then break camp after practice Thursday morning. ... SS Jordan Babineaux bested Champions Tour golfer Tim Simpson in a closest-to-the-pin contest at the Seahawks headquarters on Tuesday. Babineaux's shot from 70 yards ended up 4-feet, 7-inches. Simpson's closest was 5-feet.