Former Miami Dolphins running back Ricky Williams was ordered Friday to repay the team more than $8.6 million for breaching his contract when he suddenly quit before training camp.

Arbitrator Richard Bloch ruled Friday that Williams must repay $8,616,353 in bonus money under the contract he left behind when he shocked the Dolphins and their fans with his sudden retirement. The contract ran through 2007.

“We are pleased that Mr. Bloch has confirmed that Ricky Williams breached his contract with the Dolphins and is required to repay compensation,” NFL senior vice president/general counsel Dennis Curran said.

“This decision is consistent with many other cases that have affirmed the right of NFL clubs and players to negotiate compensation based on the player’s fulfillment of the contract,” Curran said.

The Dolphins declined comment Friday, saying they only talk about players on their roster.

Williams’ agent, Leigh Steinberg, was out of the country, his office said. He didn’t immediately return a phone message left Friday.

The Dolphins had filed a grievance against Williams, asking an arbitrator to uphold their contractual right to recover the money paid to him between the signing bonus and incentives. Before the grievance, the Dolphins mailed a letter to Williams asking him to report or pay the money back.

Williams also called the team, telling them he would come back if he received a new contract. The Dolphins declined that request.

Williams has given many reasons why he called Dolphins coach Dave Wannstedt days before workouts were to begin in July to tell him he was quitting. At different times, Williams has expressed displeasure with his contract, an excessive workload and new offensive coordinator Chris Foerster.

It was not immediately known what would happen if Williams declared bankruptcy or decided to return to the team.

But even if the 27-year-old Williams wanted to return, he faces a suspension for the entire 2004 season for violating the NFL drug policy. He has acknowledged testing positive for marijuana three times.

The Carolina Panthers have not had a very good week: Running back Stephen Davis was lost Friday with a knee injury, just days after star receiver Steve Smith broke his leg.

Davis and Smith are the defending NFC champions’ top two offensive threats.

Davis, who ran for a career-best 1,444 yards last season, began having problems with his knee after practice Thursday, and an MRI showed “a small cartilage problem,” coach John Fox said Friday.

He had arthroscopic surgery Friday, and will miss Sunday’s game at Kansas City. The Panthers said he would be out two to five weeks.

Smith, who led Carolina in receptions (88) and yards receiving (1,110), is out indefinitely after breaking his left leg in Monday night’s loss to Green Bay.

DeShaun Foster will replace Davis at running back, and rookie Keary Colbert is expected to start at receiver. Chris Gamble, another rookie, could replace Smith on punt returns.

“As I told the team, we have got 53 men out here we think we can start and win for us. They have got to step up,” Fox said. “It is part of the game. Kansas City is going to play without some starters. These guys understand that. It is not the first time it has happened.”

Foster was a solid backup to Davis last year, and started two games in place of him while Davis nursed an ankle injury. He ran for 429 yards on 113 carries, and had 26 receptions for 207 yards and two touchdowns.

Foster was also solid in the postseason, running for 196 yards and two touchdowns in four games.

He first proved his worth in a regular-season game at Indianapolis, filling in for Davis when he left in the second half with a bruised arm. Foster came in and carried 16 times for 85 yards to help the Panthers to an overtime victory.

Serena Williams, right, argues with chair umpire Mariana Alves, left, during her match with Jennifer Capriati at the U.S. Open in New York, Tuesday, Sept. 7, 2004. Williams came up on the losing end when Alves overruled the line judge in the opening game of the third set. Capriati went on to win 2-6, 6-4, 6-4 and moved on to the semifinals.

With rain washing out live matches, people had a chance to see the officiating error that took a point from Williams and gave it to Capriati in the third set’s opening game Tuesday night.

That replay was everywhere. Well, everywhere, that is, but the chair umpire’s stand during the match itself.

And with no new results to talk about, the buzz around the National Tennis Center on Wednesday afternoon was about whether instant replay or other tools should be used to help make better rulings. There were at least two other questionable calls in the final game of Capriati’s 2-6, 6-4, 6-4 win.

“It was such a horrendous call. If I was closer to the court, I would have run onto the court,” said John McEnroe, who called the match on USA. “I’ve seen a lot of bad calls in my day, but I don’t think I’ve seen three bad calls in a set like that.”

Not surprisingly, given his “You cannot be serious!” reputation for on-court arguments, McEnroe favors adding some form of replay to tennis.

He would put limits, though, as there are in other pro sports, such as perhaps some sort of penalty for a wrong challenge. In the NFL, for example, a team can get up to three chances per game to question calls; if it loses a challenge, it forfeits a timeout. Limited forms of replay are used in the NHL and NBA, too, but baseball has never shown any interest in trying it.

Serena Williams demonstrated that her shaky knee is holding up fine, sweeping past Patty Schnyder 6-4, 6-2 yesterday to reach the quarterfinals of the U.S. Open.

Once again dressed in black, the two-time Open champion had little trouble in winning her fourth straight match at Flushing Meadows. Williams took this one with her serving, finishing with 12 aces compared with one double fault.

Williams was forced to pull out of last month’s Olympics because of pain in her left knee. She had surgery on it in August 2003, and missed 8-1/2 months while recovering.

In fact, she said a few doctors advised her to skip this tournament.

“My knee is doing pretty good right now. I haven’t had any worries,” she said. “I’m just excited to be here because I wasn’t supposed to come.”

Williams advanced to yet another matchup with Jennifer Capriati, who beat Ai Sugiyama 7-5, 6-2.

Williams is 10-6 lifetime against Capriati, including 3-3 in Grand Slam events. Capriati defeated her in the French Open quarterfinals this year, then lost to Williams in the Wimbledon quarters.

“I like playing Jennifer a lot, I really do,” Williams said. “We always play each other. We really know each other’s games.”

Of Williams, Capriati said, “I’ve played her at her best. I’ve played her at her worst. I’ve played her at my best, me at my worst. I can just only worry about myself, really.”