LOS ANGELES — During a press conference last month on the sprawling set of "CSI," a journalist with obviously little regard for his own well-being asked Laurence Fishburne if he was intimidated by the notion of joining TV's top-rated drama.

"No," the actor smoothly replied with the rich, booming baritone that inspired the downtrodden to rise up against the machines in "The Matrix" and frightened the funk out of Tina Turner in "What's Love Got to Do With It?"

His brief response hung in the air for a few awkward seconds until both cast and reporters burst into laughter.

"It's Laurence Fishburne, man," someone cracked.

You bet it is. And that may prove problematic. Fishburne, whose last regular TV gig consisted of galloping around "Pee Wee's Playhouse" in a cowboy outfit, is stepping in for lead actor William Petersen, who left the series after 8 1/2 years to dedicate more time to tackling theater roles and, presumably, rolling around in the mountains of money he collected as both star and executive producer.

Petersen never received much critical praise for his performance as Gil Grissom, an unkempt, self-contained Sherlock Holmes with an unhealthy curiosity toward insects, but his understated approach established the mood of the series.

Fishburne's character, Raymond Langston, a professor who lectured on the criminal mind before joining the team as an investigator, is decidedly different in both tone and posture. (Fishburne can't help but look 7 feet tall and fully prepared to snap the neck of anyone who challenges his authority.)

The contrast between the two performances was most apparent in Petersen's final episode, when the two teamed up to stop a serial killer. Langston, frustrated by the slow pace of forensics, decided to play a mind trick on a key accomplice, hoping the man would slip and reveal the whereabouts of the murderer. Grissom, on the other hand, headed to the lab to locate the site by analyzing the position of the moon from various photos.

In any other detective series, the showier approach would save the day, but in "CSI," it's the methodical, scientific route that has always led to the bad guy. Langston got outwitted by the would-be sap.

Just how much Fishburne will play second fiddle to the drama's formula, and how much audiences are willing to accept him, may be the most tantalizing mysteries of the season.

Early ratings suggest it may take some time. The first episode without Petersen drew 17.5 million viewers, a staggering number for a program that doesn't feature Simon Cowell, but about an 11 percent drop from the season average.

Kenneth Fink, who has directed nearly 50 episodes, admitted that Fishburne is still adapting to the pace of network television.

"He's a feature (film) actor, which means he's used to rehearsal time and having time to slowly set himself into a scene," Fink said while leading a tour of the bare-bones interrogation room. "I'm shooting seven or eight pages a day, while in movies, you shoot about two or three. But we're making the time for him and he's making the time for us. There's got to be give and take."

Fishburne himself is too cool to cop to any adjustment pains.

"I've heard a lot of people talk about this grind of series television, but I haven't seen it yet," he said. "I had two responsibilities coming in. One was to service the show that's been No. 1 for nine years. If it ain't broke, don't fix it. Two, I really try to blend in as harmoniously as possible. With respect to whatever input and influence I may or may not have, I will earn that as I go."

Change could be the best thing for a show that's still wildly popular but also getting long in the tooth. Later this year, the show will air its 200th episode. Co-executive producer Naren Shankar said the series has always embraced alternative approaches. An upcoming episode featuring country-music star Taylor Swift takes place over the course of a year, with each act representing a different season and a different case at a seedy Las Vegas hotel.

"We could just stick to the formula, where they find the body, investigate the body and so on, but that's not how we do things," he said. "We've got a great blank canvas. As long as we keep the spine intact, we can do all sorts of things."