"(It was) really tough to generate (pace) with it cold out there, the balls are pretty dead," said Millman after his tight Sydney International quarter-final loss to Gilles Simon which finished well after 1am on Friday following a wet night.

"The balls are really shit when it gets like that, I figured out, so I've got to factor that in for next week in Melbourne, just remember how bad the balls are in cold conditions like that.

"Obviously it's a new ball. It made it tough at the end there. But at the end of the day it was the same conditions ... and Gilles was better."

Dunlop has taken over from Wilson as ball supplier this Australian tennis summer.

Tomic spoke out against the balls after using them at the Kooyong Open, saying "I don't feel it is that good of a ball. I think they're pretty cheap from what I've heard."

But others including fellow Australian star Ashleigh Barty have no problem with the balls.

"I like them," Barty said at the Sydney International this week. "They are not much different from the previous Wilson ball and I think they are a very fair ball."

Australian Associated Press