Brook left in limbo by Alexander
Sheffield native Brook, the mandatory challenger for Alexander's welterweight belt, was nearing the end of a 13-week training block in Spain ahead of their title fight when the American pulled out with a bicep injury.
The bout, originally set for 19 January, had already been delayed until February 23 when Brook hurt his ankle in December, but he had hoped to set a third date with Alexander within next two months.
However, days after Alexander's withdrawal, WBC welterweight champion Mayweather revealed that talks for the pair to meet in a unification bout in May were underway, a situation that would freeze Brook out of title contention for the time being.
Should Alexander line up a fight with Mayweather - the only fight he could arrange other than a showdown with Brook - the 26-year-old admits his own future remains unclear.
"I still don't know - I'm still in limbo with it all," Brook told Sky Sports News. "I'm absolutely gutted. I've been training for 13 weeks, then I heard from my family. Finding out the news, I can't put into words how devastated I am.
"But I've got to be professional about it. I've got to keep ticking over, keep my mind on it and wait to hear from them.
"This kind of thing has happened to me before on a smaller scale. I've just got to keep my mind on it. It is hard to deal with, but I've just got to deal with it and be ready for what comes next."
With Mayweather's Las Vegas comeback scheduled for May 4, on the eve of the Mexican heritage festival Cinco de Mayo, it was thought that Robert Guerrero or Saul Alvarez would be likely opponents for the undefeated five-division world champion.
His latest comments have confused the situation, though Brook admits it may simply be a negotiation tactic.
"I'm not sure," admitted Brook. "I don't know if it's a ploy to get Mayweather and Guerrero fighting for the WBC. You never know what's going to happen [in boxing].
"Eddie [Hearn]'s going over for the [Gavin] Rees-[Adrien] Broner fight this week, so we should find out more then."
Nevertheless, Brook holds out hope that the fight with Alexander in Detroit might still be on the cards.
"He's been on my mind for weeks. People haven't heard of me in America - I want to get in there and rip that title off of him and explode onto the world scene.
"I've never been more ready for a fight than this one, but what do you do? Obviously now I've got to keep ticking over, watch what I eat and wait to find out.
"I don't know what to do with myself, but I've just got to stay professional."