Lendl throws over the towel at Australian Open

Melbourne: Andy Murray's new coach Ivan Lendl was courtside to watch the Scot move effortlessly into the quarterfinals of the Australian Open. He just wasn't keen for anyone to know about it.

The eight-time Grand Slam winner threw a white towel over a nearby camera, which was installed to capture his reactions during the match on Rod Laver Arena.

"I didn't know it was him that had done it until after the match," Murray said. "But, yeah, that was just the sort of thing he does. He's been doing that for years."

Lendl has also been using towels to protect himself from the Melbourne sun. Monday's temperature hit a high of 34C (93F).

Murray in quarters after Kukushkin retires hurt

It wasn't a problem for Murray, who went through to the quarterfinals at Melbourne Park for the fourth straight year when Mikhail Kukushkin retired with a left hip injury while trailing 6-1, 6-1, 1-0.

The fourth-seeded Murray didn't enjoy the experience much.

"It's just boring," he said. "There was nothing happening on the court. Didn't have to do anything. Just hitting the ball in the court and he wasn't running. He was making mistakes the first or second ball of the rally. That was it."

Murray, the beaten finalist the last two years, now plays Kei Nishikori of Japan. He could meet two-time champion Novak Djokovic in the semifinals.