SAN DIEGO -- It's true -- the Chargers' season hasn't started and Ted Cottrell has already lost his hair.

But don't worry about the team's defensive coordinator. His smooth scalp is courtesy of a razor, not fretting about what lies ahead.

Cottrell feels better about his unit this year, after growing pains last year had some questioning the new coach's wisdom. But that cloud of doubt quickly dissipated once the Chargers righted themselves after a 1-3 start.

This year? Cottrell can't wait to begin, while hoping his defense continues to grow -- unlike his hair.

What's hairy is monitoring Pro Bowl linebacker Shawne Merriman. He's playing with two torn knee ligaments, and among Cottrell's assignments is keeping a close eye on him.

"It's how he feels," Cottrell said of Merriman's playing time. "If he is feeling well, his reps will be up a little bit. If not, they'll be lower. We won't know until he gets going in the game.

"I can't tell how long he is going to go. Hopefully, he can go a whole game but we are not going to ask him to do that."

If Merriman is fit, Cottrell turns loose the NFL's leading sacker over the past three seasons. If not, Cottrell's got that covered, too.

"We are prepared if he wants to play a lot, and we are prepared if he can't go much at all," Cottrell said. "Both ways, we are ready."

Cottrell was also prepared for Merriman to not to play at all. But Cottrell said once Merriman made his choice, he accepted the decision -- whatever it might have been.

"When I talked to him about it, he said he wanted to do it and I said, 'are you sure?' " Cottrell said. "He said, 'yeah' and he had no reservations -- he had his mind made up. I said, 'OK, lets go to work.'

"Whatever he decided was fine with me; I wasn't about to push him into doing something that would hurt him or whatever. I told him his career is foremost in our minds; he is a young player."

So Cottrell doesn't grow older faster, orchestrating a defensive plan minus one of the NFL's most disruptive players.

"Geez, we would not be as good -- he is not in the Pro Bowl for no reason," Cottrell said of a Merriman-free defense. "He is a heck of a player and if he's not playing, we are missing him."

Rivals think otherwise.

"The offenses would like for him not to play, I know that," Cottrell said.

The Chargers defense, for the most part, played well last season and helped the team to its fourth AFC title game in franchise history.

It led the NFL with a plus-24 takeaway margin, the first time since 1993 it earned that distinction. The defense also had a league-best 30 interceptions -- its most since 1969 -- and 48 takeaways. The Chargers had never paced the NFL in those categories -- until Cottrell arrived.

Beginning Sunday against the Carolina Panthers, Cottrell wants to build on that success, not rest on it.

Cottrell, a 24-year NFL veteran, said there are two areas in which the defense can improve.

"Our third-down percentage needs to get better," said Cottrell, the Chargers allowed a nearly 40-percent conversion rate. "What we need to do better is on first and second downs, to get to third-and-long. The percentages are much greater at third-and-long."

Also catching Cottrell's attention this summer was the Chargers' tackling -- or lack of it.

"I know it's preseason, but we need to make sure we are tackling," Cottrell said. "We have been working hard on that in practice, believe it or not."

While the Chargers can't knock the daylights out of each other in workouts, they can hone their technique.

"You can't go full speed, but you can have a little bit better form, and I remind them what they have to do," Cottrell said. "Plus, having a lot of guys running to the ball. That way if someone does miss, there is enough people around there to take care of him."

Cottrell has been around long enough to know the Chargers can't go to sleep on the Panthers, that opening games can be tricky, especially when it's an opponent not in the same division or conference.

"Their quarterback (Jake Delhomme) is healthy and he's very experienced -- he has been to a Super Bowl," Cottrell said. "And they added the running back (Jonathan Stewart) and they have a great offensive line."

It's an offense missing its biggest weapon, though, suspended wide receiver Steve Smith.

"But they still got (Muhsin Muhammad) and D.J. Hackett may be back," Cottrell added.

Cottrell speaks, then removes his cap as if to run his fingers through his hair. Some habits die harder than others.

Chargers notes

The team still needs to sell some 600 tickets by Friday afternoon to lift the local TV blackout of Sunday's game. The Chargers received a 24-hour extension from the NFL. … Coach Norv Turner is optimistic that LT Marcus McNeill (neck) could return to practice soon, after he saw another specialist on Wednesday. McNeill, who missed the preseason games, won't play on Sunday. … Most of the ailing Chargers worked Thursday: OLB Shawne Merriman (knee), TE Antonio Gates (toe) and DT Jamal Williams (knees) practiced, while C Nick Hardwick (foot) and McNeill were out. … As the season grows closer, more people approach WR Chris Chambers regarding fantasy football leagues. "It's mostly my friends, but they tell me they drafted me," Chambers said. "They want to see me do good, and I told them I'll score some touchdowns for them." … OL Willie Anderson, a free agent the Chargers had an interest in, signed instead with the Ravens.

Contact staff writer Jay Paris at jparis8@aol.com.