Murray rolled over on his right foot during his second round thrashing of Russian teenager Andrey Rublev, losing balance as he reached for a forehand and tumbling to the floor.
He took treatment from a physio at the next change of ends and later told his box, “my foot is killing me”.
However, he appeared unhindered as he strolled through the final six games on Rod Laver Arena and sealed a 6-3 6-0 6-2 victory. He will now face American Sam Querrey in round three.
“It’s a little bit stiff just now. It’s okay. I don’t think I’ve done too much damage. I heard a few crackles and it was sore. It was throbbing kind of for the rest of the match. I was moving fine on it though. It was just sore. So you’re thinking about it because you have a little bit of pain when you’re moving around,” Murray said.
Roger Federer said he was disappointed after scrapping his way to a 7-5 6-3 7-6 (7/3) win over America’s Noah Rubin and into the third round.
A straight-sets win in just over two hours hardly sounds like cause for dejection but Federer’s fitness and usual finesse both appeared lacking here, against an opponent ranked 200th in the world, playing only the fifth grand slam match of his life.
The 17-time grand slam champion will hope greater rhythm returns with more time spent on court given he now faces a far tougher challenge against world number 10 Tomas Berdych.
“I was just not doing what I was trying to do. I was hoping to play better at times,” Federer said.
“I think you can always do better. It’s one of those sports like golf, you can always leave frustrated. Like tennis, you can feel: ‘I could have always played a little bit better’. I guess I was hoping to play better offensive tennis.”
Angelique Kerber revelled as Rod Laver Arena sang her happy birthday but it was not all smiles for the top seed against Carina Witthoeft in the women’s second round.
Kerber, who turned 29 yesterday, was made to dig deep for her 6-2 6-7 (3/7) 6-2 victory over her German compatriot, who led by a break in the decider, after winning nine points in a row.
There was an angry swish of the racket from Kerber, who for a short period lost focus before finally rediscovering her groove to book her place in round three.
She will now play world number 58 Kristyna Pliskova, the twin sister of Karolina, whom Kerber beat in the final here last year.