UFC lightweight contender Dustin Poirier has revealed who he believes is the toughest fight in the highly-stacked 155 pound division.

When one considers the top three fighters in the division, it is the current top three ranked guys in current champion Conor McGregor, interim champion Tony Ferguson and number two ranked Khabib Nurmagomedov.

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Poirier himself, is looking to climb up the rankings, having most recently defeated former lightweight champion Anthony Pettis via TKO (submission) on 11 November.

The win in Norfolk drove "The Diamond" all the way up to number seven in the rankings and when asked on the Anik and Florian podcast who he found the toughest fight, Poirier, despite already having been knocked out by McGregor in the featherweight division, replied with Nurmagomedov.

"It's tough to say," Poirier said. "But probably keeping Khabib off your legs and building back up...then stopping him for 25 minutes would be the toughest fight, the most grinding fight."

Poirier also offered his thoughts on McGregor, who is still yet to defend his lightweight title since winning it in November 2016, making it nearly 13 months without a title defence.

The Irishman was expected to unify the titles against Ferguson, however, there is no update on when he will actually return with his punishment yet to be determined for his recent actions at Bellator 187.

"As far as Conor man, is he going to fight at 155 or is he going to box again, what's going on? Something needs to happen," Poirier explained.

"I don't know [if he should be stripped]. I'd hate to see a guy get stripped of the belt, you know, the guy earned it.

"But what are some of the past stuff they've done with other champions who haven't defended in over a year? I'd go off of that. If they stripped people before for not defending in 18 months [if McGregor defends in April] or whatever it's going to be, maybe take the belt from him."