Former undisputed middleweight champion Jermain Taylor, who has lost four of his last five fights, including three by crushing knockout, withdrew Tuesday from Showtime's Super Six World Boxing Classic.

Taylor was due to face super middleweight titleholder Andre Ward in the second stage of the modified round-robin tournament on April 17.

"I'm going to take some time off from the sport of boxing and take myself out of [the] Showtime Sports World Boxing Classic tournament," Taylor said in a statement. "It's important that I give my body and mind some much-needed rest, because I have been boxing for nearly 20 years. I plan on keeping myself in shape and making a return to the sport sometime in the future."

The 31-year-old Taylor fought twice in 2009, but was brutally knocked out in the final seconds of each bout. In April, Taylor challenged Carl Froch for a super middleweight title and was stopped with 14 seconds left; at the time he was leading on the scorecards.

Then, in the opening round of the Super Six tournament in Germany on Oct. 17, former middleweight titlist Arthur Abraham knocked Taylor out cold with six seconds left and left him hospitalized with a severe concussion and short-term memory loss.

Since then, there has been heavy speculation about Taylor's future in the six-man tournament, especially after Lou DiBella, the fighter's career-long promoter, resigned over concerns for his health -- even though DiBella stood to earn hundreds of thousands of dollars had he continued to work with Taylor through two more guaranteed tournament bouts.

DiBella was pleased that Taylor took his advice and withdrew from the tournament.

"I know it must have been a difficult decision for Jermain and I'm very happy for him and his family that he decided to give himself a much-needed break," DiBella told ESPN.com.

Behind the scenes Taylor's manager, Al Haymon, had been working with Showtime on a buyout of Taylor's remaining tournament fights. It is unclear what sort of deal they reached, if any, before Taylor's announcement.

"This was not an easy decision for me, having discussed it with my family, trainer [Ozell Nelson], friends and my adviser, Al Haymon, because I'm a very competitive person. But I know this is the smart road for me to take," Taylor said. "I want to thank Showtime Sports for everything and I wish the best for my five counterparts who will continue on in the Super Six tournament. Most of all, I want to thank the many fans for their continued support."

The field for the Super Six includes Ward, Abraham, Froch, former titleholder Mikkel Kessler, whom Ward beat in the first round to win the belt, and Andre Dirrell.

Taylor's replacement is likely to be the winner of a fight between Sakio Bika (28-3-2, 19 KOs), champion of the 2007 "Contender" tournament, and Allan Green (29-1, 20 KOs). Their handlers are working to finalize a fight between the two for Feb. 5 on Showtime's "ShoBox" series. DiBella promotes Green and Haymon manages Bika.

Although Taylor's withdrawal has been a possibility for months, the Bika-Green fight was conceived as a way to determine an official alternate for the tournament in the event any of the six participants pulled out.

Late last week, DiBella told ESPN.com that "Allan has agreed to the fight and Bika and Al Haymon are working on their side."

If Bika and Green fight to a draw, DiBella said the winner of a coin flip would become the alternate. If an injury forced the fight to be called off, the healthy fighter would get the open spot in the field.

If Taylor ends up retiring for good, his achievements in his nine-year professional career are many.

After Taylor (28-4-1, 17 KOs) received the bronze medal in the 2000 Sydney Olympics, he turned pro under DiBella's guidance and in 2005 outpointed Bernard Hopkins via split decision to win the undisputed middleweight crown. Taylor's victory ended Hopkins' division-record 20 consecutive title defenses. In the rematch -- Taylor's first defense -- five months later, Taylor outpointed Hopkins in a unanimous decision.

Taylor, of Little Rock, Ark., would go on to make defenses against Winky Wright (a draw), Kassim Ouma and Cory Spinks before meeting mandatory challenger Kelly Pavlik in September 2007.

In that fight, Taylor knocked Pavlik down in the second round and was perhaps a punch or two from ending the fight before Pavlik rallied and stopped Taylor in the seventh round to win the title.

Taylor was never the same after that. He moved up to super middleweight and lost a decision to Pavlik in a nontitle, immediate rematch in February 2008. Later in the year, he won a decision against Olympic teammate Jeff Lacy, a former super middleweight titleholder on the downside of his career, before suffering nasty knockout losses to Froch and Abraham.

Dan Rafael is the boxing writer for ESPN.com.