Roger Federer is disgruntled with the Australian Open tennis balls as they suit the playing style of Novak Djokovic, according to Jim Courier.
The weather conditions in Melbourne have been extremely variant from day-to-day which affects the speed of the balls.
During the hot days the balls tend to fly off the courts and bounce much higher.
But in the much cooler night sessions, which Federer joked were “frosty”, the tempo is slowed down.
World No 3 Federer has played three of his four matches in the prime evening slot and Courier believes he is not happy with the balls.
“Roger Federer is probably not very happy about the balls as they get big and heavy after just a couple of games,” Courier said.
Jim Courier says the Australian Open conditions do not suit Roger Federer
“The balls are heavy and they are not bouncing up and I think the court suits Novak Djokovic better. “Rafa [Nadal] would have been the favorite against most of the people but not if he faces Novak Djokovic in the final again.”
Federer spoke about how the conditions affected the ball after his second-round win over Filip Krajinovic.
He said: “These conditions here, especially in the night or under the roof where I’ve played twice now, you can start seeing the ball extremely clear as there’s no wind, no shade and sun.
“It does feel sometimes like a bit of a clay court where you can maneuver your opponent around until he’s not there any more, and you can just – I don’t want to say you can hit it in the open court, but it’s easier to construct the point and end up with a winner.
“Whereas if it’s faster, you have to hit it on the back foot sometimes. You hit it late and you hope it stays in.
“This is why you see us either having a lot of unforced errors or a lot of winners.
“Then, of course, statistics don’t always mean everything, as well, as we saw with his first-serve percentage. You would think you couldn’t be broken that often.
Roger Federer takes on Tennys Sandgren in the quarter-finals
“Like I said on court, as well, I think conditions played on the faster side when the balls are new, then it gets extremely slow once they fluff up.”
Federer takes on world No 100 Tennys Sandgren for the first time in his career in the quarter-finals.
And the Swiss star has been handed the day session on Tuesday so his match is expected to get underway around 3am GMT.