I don't know if he's up to it. That's the spirit I'm paying to see. There are some that do reach deep, of course. Aaron Krickstein was famous for his comebacks in 5-setters. Just guts . . .
Tenacity is more than overall match-level determination.
It's about point by point, shot by shot, maxed out concentration. Winning tennis is very much about statistics. A few screaming winners don't win the match. A lot of unforced errors do tend to lose the match. Many points are wasted by not being totally focused at the start.