"I have heard it from Matt Hughes' mouth that this will be his last fight -- I think win or lose," Bonnar said on this week's "MMA Live" on ESPN.com.
The possibility for retirement is there as the fight against Serra is Hughes' last fight under his current UFC contract and the 35-year-old has lost three of his last four fights.
However, Hughes (43-7) told the press differently at the media conference yesterday at the MGM Grand Garden Arena.
"I got in this sport for one reason, and it was to compete," Hughes said. "I just love to compete. I never thought I'd be world champion. Never thought I'd make enough money to support my family, so that's it. That competition is still keeping me where I'm at. When I lose that desire to compete, that's when I'll be looking for the door and Dana [White] and I will be talking about going down some other avenue, but right now I still love getting in there and mixing it up with one of the guys."