By Radio Rahim

Top Rank's CEO Bob Arum, who promotes WBO welterweight champion Terence Crawford, views Amir Khan as a tough opponent for his boxer.

Arum has presented a guaranteed offer of $5 million to Khan to face Crawford on March 23 at Madison Square Garden in New York, on ESPN Pay-Per-View.

But Khan also has an offer to face his domestic rival Kell Brook, in what would be a much bigger money fight back home.

Arum has no idea how the negotiations will play out, but he cautions that Khan is not an easy opponent as some critics have suggested.

"I've talked to Amir Khan, he seems interested in the fight. We'll have to see. I think it would make for a very interesting fight. I think Khan feels that he can give Crawford a real fight. We'll have to see, but it's not a done deal yet," Arum told BoxingScene.com.

"Crawford is not a big welterweight. He's a small welterweight. Khan is much bigger physically. Do I think Crawford beats Amir Khan? Yes, I think he beats him. But it is not an easy fight. Khan is a very, very slick, good boxer - and he showed that with Canelo, but Canelo was too big for him and ended up knocking him out."

In a recent interview, Khan seemed to be leaning in the direction of facing Brook, after the Sheffield fighter had a lackluster performance against Michael Zerafa.

"Crawford looked bigger to me because he's got a world title and he's one of the pound-for-pound best so that would have been a massive fight, but on top of that was Kell Brook's performance," Khan said to Daily Mail.

"I'll be going into this fight now favourite to win and probably knocking him out. I won't get credit for it, though, I'll beat him and they will still say, 'Oh, he was finished anyway'. I wish this fight had happened sooner. The reason it didn't is because he was running his mouth off. If he didn't do that it would have been different, but I still think it's a really big fight now and one that I win."