Hendricks, who lost a controversial split decision to St-Pierre at UFC 167 last November, fights again for the 170-pound crown next Saturday when he faces veteran (Ruthless) Robbie Lawler at UFC 171.
The 32-year-old St-Pierre vacated the title in December, saying he needed time away from the sport.
St-Pierre has been making the most of his time off, travelling and speaking his mind about what he believes needs to be fixed in the world of mixed martial arts.
But he remains close to the sport and says he will be watching the UFC 171 main event in Dallas.
"It's a fight where anything can happen," St-Pierre told The Canadian Press. "Both guys can put each other to sleep. They have a lot of power in striking, but I believe Hendricks has the edge in this fight because I believe he will come more well-prepared with his team and he's got an edge in the grappling department."
Hendricks (15-2) is a former two-time NCAA wrestling champion.
St-Pierre (25-2) left a 12-fight winning streak and a string of UFC records behind him. But he says it won't be strange seeing someone else have his belt strapped around their waist.
"No, because it was my choice to give away the title. It was my choice so I don't regret anything. I feel very good and I'm happy that I did it. I feel better now."
St-Pierre, who had held the UFC title since regaining it from Matt (The Terror) Serra at UFC 83 in April 2008, says the outcome of the fight will not affect whether he returns to the sport.
"I don't plan on coming back right now," he said. "First if I come back, it will be when I want. I have a lot of things to do. And also a couple things need to change if I come back. ... Whoever wins, I don't care. I just watch it as a fan."
Since leaving the sport, St-Pierre has spoken out about the need to have more stringent drug testing. The Montreal fighter — who was the UFC's biggest pay-per-view draw — has also complained about the UFC having a monopoly.
Hendricks has said he sees Lawler (22-9 with one no contest) as a more dangerous opponent that St-Pierre.
"Robbie, if you make a mistake, we've seen it time and time again that he can knock you out."
The 30-year-old Hendricks is the top-ranked contender in the 170-pound division while Lawler is No. 3.
No. 2 Carlos (The Natural Born Killer) Condit, who lost to St-Pierre in a UFC 154 title shot and was beaten by Hendricks at UFC 158, takes on No. 11 Tyron Woodley (12-2) in the UFC 171 co-main event. Condit (29-7) says he has been told a win will earn him another title shot.
Hendricks is currently No. 10 in the UFC's pound-for-pound rankings.