Rafael Nadal welcomes potential innovation in tennis, but the world number one unsurprisingly said he preferred no changes.

Several rule changes are being trialled at the Next Gen ATP Finals in Milan, including first-to-four games sets, a shot clock and no line judges.

Nadal said he was happy to see tennis embrace new ideas, even if the sport opted not to stick with the innovations.

"All the things that you can try, I welcome," the Spaniard said on Friday, ahead of the ATP Finals.

"I don't know if that's the way or not, but in some way, the fact that we are trying new things – always trying things – you can find a better way. If we don't try anything, then you cannot say that that works better or that works worse.

"Nothing is perfect. The net's stayed the same height as 50 years ago and the people are taller.

"It's something we need to find a way to have the best show possible."

Nadal said the players should eventually decide on the ideas, but the 16-time grand slam champion is more than happy with the sport the way it is.

"The players will all have to decide about these sort of things because we are affected," he said.

"If you ask me if you want changes, I will say no. I am world number one of the world and I have achieved a lot of things.

"If the game needs something to be more attractive for the fans, then that's the way the game needs to move forward."