The former defender believes the Argentina forward is in a league of his own and has backed him for yet more individual success, while hailing the work of Jose Mourinho
The Argentine forward has lifted the trophy in each of the last three seasons and is on course to win it for a fourth consecutive year, following a record breaking haul of 50 goals last term.
"If you look at it in terms of pure quality and talent, then Messi is untouchable," Sagnol told fifa.com
"It's a little more open if you bring club and national team results into it, though when it comes down to natural talent there's no one who's at Messi's level."
Messi's closest rival is likely to be Real Madrid forward Ronaldo, with the pair leading a 23-man shortlist dominated by attacking talents, something Sagnol accepts despite his allegiance to the art of defence.
"The Fifa Ballon d'Or has always gone to attacking players, and as a defender I've never found that frustrating," he continued.
"Football is a sport that is there to make people dream, and that's something a defender can't do, which is normal in my mind.
"The Ballon d'Or should go to players who can do that, Lionel Messi can make people dream, and Cristiano Ronaldo too. Those are the players it should go to."
The 35-year-old also gave his thoughts on the contenders for the Coach of the Year prize and singled out one man in particular for special praise.
"If I had to choose one, I'd go for [Jose] Mourinho, even if his behaviour rubs people up the wrong way sometimes," he added. "He gets the best out of his players and he gets results wherever he goes. You just have to take your hat off to him.
"The only way you can judge a coach is by seeing what he's won. A coach who wins things must be good at what he does, and the likes of [Sir] Alex Ferguson, Jose Mourinho and Pep Guardiola do it better than anyone else."