Tennis isn't just about the technicalities of hitting a tennis ball - it's about a struggle between two individuals. I think it adds a good frisson when players genuinely dislike each other. That's why I'm hoping there's more of this stuff from the Kyrgios/Kokkinakis generation. Every time one of the big four beats another in a slam, it's all respectful hugs and syrupy remarks. For once I'd love Djokovic to come out and say "I've beaten Roger's ass here, I'll beat his ass at the next slam. You should retire old man because otherwise I'll destroy your reputation."