Welterweight titleholder Devon Alexander's mandatory defense against Kell Brook has been rescheduled for Feb. 23 because of Brook's recent ankle injury, Golden Boy Promotions chief executive Richard Schaefer told ESPN.com on Monday night.

The fight, a Showtime-televised main event, was originally scheduled to take place Jan. 19 at the Nokia Theater in Los Angeles. However, England's Brook injured his ankle last week, and Schaefer and Showtime have been working on a new date.

Schaefer said the fight now will headline a Showtime tripleheader in Detroit that will also include junior middleweight titlist Cornelius "K9" Bundrage (32-4, 19 KOs), who is from Detroit, making his third defense against Ishe Smith (24-5, 11 KOs) of Las Vegas. Schaefer said there would be one other televised fight to be determined.

"We'll have two world title fights, and it could turn out to be three, so if we bring three world title fights, including one with hometown champion 'K9' Bundrage, I think we will do darn well there. Detroit is a great fight town," Schaefer said.

Brook suffered the injury in a recent training session, according to Matchroom Sport promoter Eddie Hearn.

"Kell sustained an ankle injury that has hampered his training and running work," Hearn said. "I'm concerned mainly for the traveling U.K. fans, and it's in no one's interest for the fight to fall through closer to the time, so I requested a three- to four-week delay to the original date of Jan. 19. This will eradicate the risk and ensure Kell will be 100 percent for the biggest fight of his life."

St. Louis' Alexander (24-1, 13 KOs) won a version of the 147-pound title Oct. 20 with a lopsided decision against Randall Bailey at the Barclays Center in New York. On the same day in his hometown of Sheffield, England, Brook (29-0, 19 KOs) knocked out Argentina's Hector Saldivia in a final elimination bout to become Alexander's mandatory challenger.

The two fights originally scheduled for Jan. 19 on the Alexander-Brook televised undercard -- interim junior welterweight titlist Lucas Matthysse (32-2, 30 KOs) of Argentina against Philadelphia contender "Hammerin'" Hank Lundy (22-2-1, 11 KOs), and a welterweight scrap between Selcuk Aydin (23-1, 17 KOs) of Turkey and Mexico's Jesus Soto Karass (26-8-3, 17 KOs) -- will still go forward but they will take place Jan. 26 instead of Jan. 19.

Schaefer said that rather than compete with an HBO tripleheader on the same night, Showtime Sports general manager Stephen Espinoza asked him whether he would consider moving the card a week later. Schaefer said he would, but because the Nokia Theater is not available, he is looking for a new venue. Schaefer said the card would likely take place elsewhere in Los Angeles or in Las Vegas.