“I couldn't give up, so I finished the match” (ATP Finals)

This problem with the balls that you regularly mention, will it lead you to try something different for next season?
That's the goal. We will try, yes. I feel like I can still win against a lot of players. I could have won this match if I had been in better shape or if I had been a little luckier. We don't know what yet, but we'll try something, yes. We'll see what I can do best. But with bullets, I feel at a disadvantage. I can find the solution during some matches, but… Today, anyone can hold the long rallies.