The 32-year-old became WBA mandatory challenger to earn a shot at unified super-welterweight champion Jarrett Hurd after grinding out a unanimous decision win in front of his home crowd in Sheffield.
Brook, who has lost just two of his 40 fights against Gennady Golovkin and Errol Spence Jr, admitted his performance was ‘rusty’ and ‘flat’.
Matchroom boxing boss Hearn believes the underwhelming display from Brook could convince long-term rival Khan to take the fight.
“I think if I was Amir Khan, I’d be on the phone to take this fight,” Hearn told Sky sports.
“Kell knows that was below par, and he’s had a long time out of the ring but every time they fight, one becomes the favourite and one the underdog.
“After Khan boxed (Samuel) Vargas, Kell became the favourite, and check with the bookmakers after this one, Khan will become the favourite.
“He makes his own decisions, and we can’t just wait on that. He is the mandatory for Jarrett Hurd now, if he wants to stay at 154lbs.
“He knows he’s got to be a lot better than that and he will be.”
Having only fought twice since the start of 2017, Brook – who said after the weigh-in: ‘I’m not interested in what Zerafa’s going to do, I’m going to be 100 per cent, no man can deal with me on Saturday night’ – made no excuses for going the distance.
“It was harder than I expected, it was a bit rusty,” Brook said afterwards, “The opponents might grow a pair now and think they can take care of me.
“It’s the best training camp I’ve ever had, tonight I was a bit flat. we all know I have it in my arsenal to be special.”
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