After 6.5 years away, Nick Diaz is about to make his return to the Octagon, taking on Robbie Lawler … but Dana White admits he doesn’t know if the star from Stockton will fight again after UFC 265.

TMZ Sports talked to the UFC prez on Wednesday, days before Diaz is scheduled to fight for the first time since January 2015 (a no contest vs. Anderson Silva) … and we asked if the comeback meant Diaz was back now as a full-time fighter.

"I don’t know. I never know that either. We’ll take it one fight at a time," Dana told us.

FYI, it’s not the first time the men have fought. Diaz beat Lawler via 2nd round knockout way back in 2004.

Despite the long layoff, Nick’s one of the most accomplished MMA fighters of all time… with wins over everyone from B.J. Penn to Frank Shamrock.

But, with over 2,400 days between fights, will it take time for Nick to reacclimate himself to the Octagon?

"Ring rust is absolutely real and especially when you haven’t been in here that long, but you never know what to expect from the Diaz brothers. You know what everybody does though? On Saturday, they show up and they fight — that’s it!"

Valentina Shevchenko is also on the card … where she’s a MASSIVE favorite over Lauren Murphy.

Last week we asked The Bullet if she was interested in a trilogy fight with Amanda Nunes … and she said she was definitely down.

We asked White about making Nunes-Shevchenko 3 … and he warned that no one should overlook Woods.

"Obviously, you can’t look past Lauren Murphy and start looking at Amanda Nunes again. Lauren Murphy has a lot of knockdowns and submissions in her career. So, when you have women that are that size that can actually knock out other women, it’s impressive."

But, with that said, Dana made it clear he isn’t against pairing arguably the 2 best female MMA fighters in the world against each other.

"Listen, Valentina Shevchenko is a savage. I mean, her and Amanda Nunes are two of the greatest female fighters to ever walk the face of the Earth and if she gets through Lauren Murphy on Saturday, maybe there is a fight for them down the road."

We couldn’t let Dana go without asking about Conor McGregor‘s (terrible) 1st pitch at the Cubs game earlier this week … the epitome of the reason White says he ALWAYS says no when he’s asked to throw the ceremonial pitch.

UFC 266 goes down Saturday night!