British star Amir Khan is very worried for his domestic rival and fellow former world champion, Kell Brook.

Brook (36-2, 25 KOs) is ready to resume his career after suffering back to back stoppage defeats - and fractured orbital bones in both losses.

Last September, Brook jumped up by two weight divisions and suffered a fifth round stoppage loss at the hands of middleweight king Gennady Golovkin. In that contest he suffered a fractured right orbital bone that required surgery. Then in May of this year, Brook was stopped in the eleventh round, losing the IBF welterweight crown, in a mandatory clash with Errol Spence, and also suffered another fractured orbital bone, this time to the left eye, and also needed surgery.

Brook is now looking to get back in the ring by end of the year. And Khan is at the top of his hit list. Brook plans to return as a junior middleweight in his latest campaign.

But Khan believes the Sheffield boxer should retire from sport, because going any further would endanger his health. He felt Brook showed a lack of hearth in taking a knee, and allowing the referee to count him out, in the loss to Spence.

Khan himself has been out of the ring since May 2016, when he suffered a vicious knockout loss at the hands of Canelo Alvarez in the first ever boxing event at the T-Mobile Arena in Las Vegas.

"I'm very surprised he is carrying on because he can harm himself and harm his career. If I was him, or his advisors, I would tell him to retire and enjoy life. After two big losses, two bad losses as well, if he's thinking about fighting me that could be a third big loss and bad for his health," Khan told Sky Sports.

"In his last fight against Errol Spence, he took a knee and gave up. In my opinion, he was doing really well in that fight, and he could have won it, there was only two rounds left. But he just went on his knee and didn't want any more of it. Sometimes, that tells you about someone's heart.

"Us fighters, we are into the ring until we die or get knocked out - that's the only way you can get rid of us. With Kell, I think when he showed that he gave up, and didn't want any of the punches, it just shows to me his heart is not in it."