On the 241st UFC tournament Nate Diaz will fight Anthony Pettis. This fight will take place in the welterweight division. Nate recently visited Ariel Helvani on MMA Show on Monday and during the broadcast, said he has no plans to return to the lightweight division:
"I have nothing to do there. I've already done everything. I'm the king of this division," Nate said.
Thus, if the bosses want to organize the third UFC fight between Diaz and Conor McGregor, they will have to do it in welterweight.