Rafael Nadal could become the new number one but he needs to win the Western & Southern in Cincinnati while hoping that Medvedev exits before the quarterfinals.
The Russian did not look too sharp in Montreal losing to Kyrgios and if he does it again, he might lose his number one ranking. It's unlikely because the only way that happens is if Nadal wins the event as well which seems tricky for the Spaniard. Even if he doesn't get it this week the opportunity to be battling for it will remain for the rest of the year and Nadal is excited about it:
“It means a lot to me to have that opportunity [to rise to No. 1]. Something that I didn’t expect could happen again. The main thing is to stay healthy and play the events that I want to play. I will not play more than what I believe works well for my body."
“I am going to put all my efforts into every single event I play. It is something that doesn’t matter if I have the chance to be No. 1, but I am happy to be in this position and if it happens, I will be very happy.”
Nadal doesn't expect things to go smooth or to be easy because every return after a long break is tricky:
“You need to know that when you come back after a while that things aren’t going to be perfect. You can’t expect to play at an amazing level from the beginning. Knowing that you [need to] be humble enough to fight with the tools that you have at the beginning to win the first match. Then when you win a match or two matches things change and you start to feel competitive again."