Federer recently achieved the feat of becoming the oldest world number one in tennis history at 36 years of age as he overtook Nadal in the ATP rankings after his quarter-final win over Robin Haase at the Rotterdam Open.
The Swiss legend would then go on to win the event after comfortably defeating Grigor Dimitrov in a straight set 6-2, 6-2 victory in the final on Sunday (18 February) to celebrate a remarkable 97th career title.
In what was an unforgettable week for Federer, his recent success capped off an extraordinary career resurgence that began last year at the Australian Open when he returned from a long injury layoff to win seven titles, including two Grand Slams.
While he wasn't able to end 2017 as the world number one with Nadal achieving the feat after his own career resurgence, the fact that Federer was able to reach the summit once again proves he is the best in the game, according to Wilander.
"The fact that he becomes number one fourteen years after the first time is just incredible," Wilander told L'Equipe via Express. "For me, it proves that Roger has this love for the game that goes beyond winning.
"But what is most impressive about Federer is what we do not see. That's what's happening inside. His greatest talent is not his service or forehand. It's his immutable need of love to learn and that passion for the game.
"He changes his racket. He changes his backhand technique. He changes tactics. He does not play at all the same way as he did fourteen years ago. He wants to learn every time he enters the court. It's so cool to see someone like him who loves what he does.
"We talk about his grace, the way he moves on the court. But it is this inner strength, this emotional part, fragile and invisible, that places it far in front of everyone. For twelve months, Roger is in front. He beat Nadal last year four times in a row. He's the best."
Federer is currently 345 points ahead of Nadal in the rankings and could extend that lead if he takes part in the Dubai Open, which takes place on 26 February.