Toni Nadal knows
Rafael Nadal really well and he's seen him deal with all sorts of situations on the court over the years including crying.
Nadal is a true fighter who rarely gives up on a point, game, or match. The Spaniard has pulled out some incredible wins in spite of anything that might bother him and that includes injuries. His heroics at Roland Garros last year are well-documented. Toni Nadal watched him play in pain many times and he spoke about that in Break Point:
"There are moments during matches where, I don't know about you, but I know Rafael gets nervous. There are moments where I look at Rafa and I can see that he's crying."
The quote speaks to the commitment Nadal had to his craft during his career as well as the pride to basically never retire. Even this year at the Australian Open, Nadal finished a match he knew he couldn't win because he didn't feel right retiring as the defending champion.