UFC welterweight champion Kamaru Usman is closely monitoring the progress of rival Khamzat Chimaev.

The Swedish-born Russian has been on an absolute tear through the 175lbs division having won each of his first four fights by stoppage.

He stopped John Phillips and Rhys McKee within just ten days of each other in July 2020.

Then the 27-year-old destroyed Gerald Meerschaert in just 17 seconds in Las Vegas in September later that same year.

Last time out 'Borz' scored a stunning first-round submission victory over Li Jingliang at UFC 267 in October last year.

And Usman has told Chimaev to essentially keep doing what he is doing as it's getting him noticed.

During an appearance on The Jim Rome Show, he said: “That’s the thing - there’s a reason there’s a structure to get here.

“He’s done great with the opposition that he’s been presented and by the time he gets here, once he gets here, of course, we’ll have that conversation.

LAS VEGAS, NEVADA - FEBRUARY 13: In this handout image provided by UFC, Kamaru Usman of Nigeria reacts after his victory over Gilbert Burns of Brazil in their UFC welterweight championship fight during the UFC 258 event at UFC APEX on February 13, 2021 in Las Vegas, Nevada. (Photo by Jeff Bottari/Zuffa LLC via Getty Images)

"But I am the champion. I am the pound-for-pound best in the world. I am the king of the castle.

“Everybody wants a piece of me, so that’s good. I like that. There was a time when I was coming up and I just couldn’t get those fights. I couldn’t get the next guy to step in there with me.

"But now that I’m at the top, I don’t have to do that. These guys have to call me out, and these guys have to come to me. So when they make it up here, I’ll be here waiting.”

In an interview with MMA Fighting quoted by BJPenn.com, Alexander Gustafsson was asked about Chimaev's brutal training schedule.

He replied: “He works harder than I ever worked.

"He’s doing five sessions a day, at least. In my prime, when I fought Jon [Jones] and those guys back in the day, I did three sessions a day, and I did, like, 20 rounds every sparring [session].

"My conditioning was crazy. But this guy, he outworks me. He doesn’t get tired.

"I better keep my hands up. I’m not kidding. He hits hard.

"He has this thing that he’s fast, and he has very good precision, so he doesn’t need a lot of power to just knock people out, because he knows what he’s aiming at, and he hits every time.

“I’ve play-sparred with lot of guys, you’re just laughing and joking around and having a good time. But this guy, when he comes to spar, he comes to spar. It doesn’t matter if it’s me or another guy, he just goes.”