|Australian Open 2017|
|Venue: Melbourne Park, Melbourne. Dates: 16-29 Jan|
|Coverage: Daily live commentary on BBC Radio 5 live sports extra; live text on selected matches on the BBC Sport website; TV highlights on BBC Two and online from 21 January.|
Great Britain's Andy Murray and Dan Evans will both be playing in the last 16 of the Australian Open on Sunday.
World number one Murray, 29, plays Germany's Mischa Zverev, who is 50th in the rankings, before Dan Evans faces France's 12th seed Jo-Wilfried Tsonga.
"It was a goal to make the fourth round of a Slam this year," said the 26-year-old, who is ranked 51st in the world.
"It's satisfying, but I'm not looking back. Whatever happens, it's been a great tournament, but there's still some tennis to be played."
Tsonga, an Australian Open finalist in 2008, is expecting a tough challenge in their match, which will not start before 05:30 GMT.
"He's very talented, he can do everything," said Tsonga. "He can play short points or rallies and he's got a one-handed backhand which isn't easy to control."
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Murray is expected to be in action at about 03:00 GMT on Sunday and thinks he will have to change his tactics against Zverev.
"He has a very different game style to most of the guys now, he's serve-volleying, coming forward as much as possible," said Murray.
"He doesn't serve like 220km/h. He serves 185s, 190s, but places it well. People say you can't play that way any more and be successful, but he's done that the last few months."
Zverev, the older brother of 19-year-old rising star Alexander Zverev, who lost to Rafael Nadal in the third round, hopes to frustrate the Scot.
"If he plays his best tennis, obviously I don't have a lot of chances, but it'll depend on the day,'' said Zverev. "Let's see if I can annoy him a little bit. If I'm serving well and not missing any volleys, maybe I can do some damage.''
The last time two British men made the quarter-finals of the same Grand Slam tournament was in 1997 when Tim Henman and Greg Rusedski reached the last eight at Wimbledon.
Murray can do 'remarkable things' - Agassi
Murray has lost in five Australian Open finals, but the man he lost to in four of those matches, Novak Djokovic, is out of the tournament.
Former world number one Andre Agassi thinks this could be Murray's year.
"This is a heck of an opportunity for Andy," said the American. "He's certainly come into his best years and if he lines everything up he has the runway free to do some remarkable things."