Christy Martin's return delayed

Christy Martin, the famed female boxer looking to return to the ring just months after she was shot and stabbed will have to wait a little longer.

Martin suffered a rib injury and withdrew Thursday from her March 12 junior middleweight rematch with Dakota Stone at the MGM Grand in Las Vegas. The bout was supposed to be on the Showtime PPV card, headlined by junior middleweight titlist Miguel Cotto's first defense against Ricardo Mayorga.

"Christy had a CT scan which revealed a fresh fracture of the fifth rib," said Dr. Robert Voy, a Las Vegas physician, who examined Martin.

"In sparring about a week ago I got hit with a hard punch to the left side, in the ribs," Martin said. "It was a good punch and it got me real good. For the next few days I tried wrapping that area but there was still pain when I tried to spar."

The blow came in the same area where she was stabbed during an alleged domestic incident at her home in suburban Orlando, Fla., in November. Her husband, Jim Martin, has been charged in the case with attempted first-degree murder and aggravated battery and is in custody awaiting trial.

Martin (49-5-3, 31 KOs), 42, has not fought since taking a 10-round majority decision from Stone (9-8-5, 1 KOs) to win a vacant women's junior middleweight world title in September 2009. It was also supposed to be Stone's first fight since the loss to Martin.

Martin had been training with Miguel Diaz in Las Vegas preparing for the fight.

"Christy was injured while sparring. She is not a complainer, but I knew she was in a lot of pain," Diaz said. "I couldn't live with myself if anything bad happened to her during a fight so we made a decision to tell the Top Rank about this."

After telling Top Rank's Bob Arum about the injury, he sent her to see Voy.

Top Rank plans to replace Martin's bout on the pay-per-view with a fight involving Baltimore Ravens safety Tom Zbikowski, if the NFL owners lock players out when the collective bargaining agreement expires.

The NFL and NFLPA agreed Thursday to a 24-hour extension to the expiration of the collective bargaining agreement, making the new deadline 11:59 p.m. ET Friday.

Zbikowski's fight cannot be formally announced until the NFL owners lock players out.

Zbikowski, who would fight in a four-round cruiserweight fight against an opponent to be determined, fought once professionally as a heavyweight on a Top Rank card in 2006.

The rest of the card remains intact. Besides Cotto (35-2, 28 KOs) facing Mayorga (29-7-1, 23 KOs), former junior middleweight titlist Yuri Foreman (28-1, 8 KOs) faces Pawel Wolak (28-1, 18 KOs) and lightweight titlist Miguel Vazquez (27-3, 12 KOs) meets Lenny Zappavigna (25-0, 17 KOs) in a mandatory defense.

Dan Rafael covers boxing for ESPN.com. Follow him on Twitter.