Joe admits Santoro could win

"The thing about beating someone like me to death is that you have to take their heart to make it work. One slip, one missed blow, one inadvertent mercy because of choosing the wrong target was a doorway for counterattack. He had a moment’s advantage where he could have—and should have—killed me. He could have used the punch that knocked out my teeth to crush my throat. He really should have. But he wanted to make it last. He was trying to hurt me before he killed me, to defeat me because I had defeated him.

That was his mistake."
-Rage pg. 439


"Last year in Oslo, he’d had a dominant moment like that and, instead of ending it right there, decided to beat me to death. He’d knocked out teeth, fractured an eye socket, and busted bones in my face. He could have used that time to kill me, and it gave me a chance to turn the tables on him."
-Relentless pg. 484