The decision was made after the 29-year-old consulted extensively with medical experts, and a call on her availability for the Constellation Cup in October won't be made until after the Quad Series.

Layton, who has been a mainstay in the Australian side for the past four years, has been replaced by Melbourne Vixens youngster Emily Mannix.

"Sharni has represented and led our country with her heart on her sleeve, but is in need of a break," Diamonds coach Lisa Alexander said.

"Our medical and support staff will continue to work closely with Sharni during this time. First and foremost we have a duty of care to the wellbeing of our athletes."

Meanwhile, battle lines have been drawn between star Australian Diamonds shooter Caitlin Bassett and England defender Geva Mentor less than two months after the pair lifted the inaugural Super Netball championship together at Sunshine Coast.

Bassett and Mentor will go head to head in this year's Quad Series opener on August 26 when Australia hosts England in Brisbane, the latter desperately keen to outline their Commonwealth Games credentials before next year's competition on the Gold Coast.

England have been widely tipped as a serious gold-medal threat to heavyweights Australia and New Zealand after Mentor headed a host of British talent who made waves in the opening Super Netball season.

Jo Harten and Serena Guthrie starred for the Giants while Ama Agbeze (Adelaide) and Helen Housby (NSW Swifts) also enjoyed strong seasons.

Australia last clashed with England in February and only managed a one-point win, the same margin New Zealand beat the Roses by in the Commonwealth Games semi-final in 2014.

"England have just grown in leaps and bounds and in particular having more players in our competition, they've really developed," Bassett said.

"It was a tight game in January, the girls I think only won by a goal so we're expecting them to come out really hard.

"We're really not taking England lightly, they've been doing a lot of hard work behind the scenes.

"They've got a lot of quality players in their team, Serena Guthrie, Jo Harten, they were playing in the final against us so we kind of know what they've got. Them playing together for the first time, it's going to be a really hard challenge."

Next year's Commonwealth Games has significantly delayed the start of the second Super Netball season, which won't begin until late April meaning it will be months before Bassett and Mentor train alongside each other as teammates again.

"Frenemies is what I would call us," Bassett said.

"Definitely friends but once that whistle blows we're going to be doing everything in our power to win for our country.

"I'm looking forward to matching up against her, I think she's the best defender at the moment by far, she was in the competition this year and it was recognised by all the awards she won so I'm looking forward to the challenge.

"We've got so many key match-ups. Me and Geva will be one of the big ones and I'm really looking forward to it and just getting back out on court and playing netball, it has been ages the last game was that grand final and that feels like years ago now.

"Commonwealth Games is always in the back of our mind and it's something that we're working towards but the focus has to be here and now and it is the Quad Series first."

The Diamonds will prepare for the Quad Series during a four-day camp at the University of the Sunshine Coast in the lead-up to their opening match against England.

QUAD SERIES

Saturday, August 26: Australia v England, Brisbane; New Zealand v South Africa, Brisbane.

Wednesday, August 30: Australia v South Africa, Canberra; New Zealand v England, Auckland.

Sunday, September 3: New Zealand v Australia, Invercargill; England v South Africa, Invercargill.