"It's not a challenge. It's an opportunity," said Martz, who was hired as the 49ers' offensive coordinator a day after interviewing with Coach Mike Nolan at the team's Santa Clara facility.

"The potential to build that offense around Frank Gore is pretty exciting. There's some outstanding pieces. We just need to tie them all together."

Martz, 56, replaces Jim Hostler, who was fired after overseeing a 49ers offense that ranked last in yards and points and yielded an NFL-high 55 sacks in 2007.

In other staff moves, Nolan said running-backs coach Bishop Harris and offensive-line assistant Mark Nori had been let go. Ted Tollner, brought in as an offensive assistant late in the season, will remain on staff in a position to be determined.

Nolan said there could be more shuffling and that he will accept input from Martz on the makeup of the offensive staff. Martz said he held wide-receivers coach Jerry Sullivan and line coach George Warhop in high regard and welcomed their return.

Nolan said he considered seven candidates for offensive coordinator, revealing three others besides Martz. Former Dallas Cowboys coach Chan Gailey was brought in for an interview last weekend, and Nolan spoke by phone with Cam Cameron and Brian Billick, who were dismissed this month as head coaches in Miami and Baltimore, respectively.

Martz, known for his brash manner, wide-open attack and aggressive play-calling, was dismissed last week after two years as the Detroit Lions' offensive coordinator.

He was the offensive coordinator with the St. Louis Rams in 1999, when they rode their "Greatest Show on Turf" offense to a Super Bowl victory. He spent the subsequent six seasons as the Rams' head coach, taking them to the playoffs four times.

During six of Martz's seven years in St. Louis, the Rams' offense, which featured frequent three- and four-wide receiver sets, ranked among the league's top 10.

In three of those seasons the Rams led the league in yards and points. Kurt Warner emerged from obscurity to become one of the league's premier quarterbacks under Martz, and Marshall Faulk was an all-purpose force at running back.

"There's no one more creative," Nolan said of Martz, with whom he worked on Norv Turner's staff in Washington in the late 1990s.

"I'm confident Mike Martz is going to use our personnel to their full potential and give us the best chance to win. He's probably, if not the best, one of the best minds in football from an offensive standpoint."

Martz said he didn't hesitate to come to work for Nolan, who's on the hot seat after three losing seasons.

"You've got to remember, I've been on the hot seat, too," Martz said. "To me, it was a no-brainer. This team is much further along and this is a much better situation" than he encountered in Detroit.

If there's a rap on Martz, it's that he sometimes has stressed the passing game to the detriment of the run. His tendency to send four or five receivers out on pass plays also can leave the quarterback poorly protected. Last season, the Lions gave up 54 sacks.

Nolan said he doesn't think that's a valid criticism. Martz went out of his way to single out running back Gore as the player he envisions as the 49ers' offensive centerpiece, likening him to Faulk.

"Frank is a little bit bigger, more physical, but he has the receiving skills and he's an unselfish pass blocker," Martz said. "He's really a complete player who shouldn't come out of the game. I think you can put him in as the centerpiece and build around that."

Martz will have the autonomy to run the offense as he sees fit, Nolan said. The coach also will rely heavily on Martz, who has worked with Pro Bowl quarterbacks Trent Green, Marc Bulger and Warner, when making the call on the starting quarterback.

Alex Smith, the 2005 No.1 draft pick who is coming off shoulder surgery, faces a training-camp challenge from Shaun Hill, provided the pending free agent is re-signed.

"Mike is the expert on quarterback play. Let's not kid ourselves," Nolan said. "I'll rely on his input. But they're going to compete on the field and the winner is going to take the job."

Said Martz: "You want them to get the ball out quickly and accurately, and I think they're both very capable of doing that."

Martz represents the fourth offensive coordinator for Smith, but Martz said it will give Smith a chance for a fresh start.