Diamonds coach Lisa Alexander is wary of an improving South Africa, as world netball champions Australia this weekend start their final tournament before the Commonwealth Games.
Quad Series matches against three of the other top five-ranked nations will provide Alexander with her final opportunities to hone the Diamonds' game style and resolve selections before the squad for April's Commonwealth Games is announced early next month.
A squad of 14 was picked for this month's Quad Series, with the Diamonds opening their campaign for that tournament against world No.5 South Africa on Sunday morning in London.
They will face third-ranked England two days later in the same city and travel to South Africa to play closest challenger New Zealand on January 28 in Johannesburg.
"Our focus is laser sharp on our performance in this three-Test series. We are looking to emulate last year's Constellation Cup, building on each and every game," Alexander said.
Competition for circle defence spots will intensify after Friday's news that 2015 World Cup-winning captain Laura Geitz has been added to the wider national squad and is eligible for Commonwealth Games selection.
This weekend's match pits Australia against a nation who have improved markedly in recent times under former Diamonds coach Norma Plummer.
South Africa, having lost all 35 of their Tests against Australia, managed to get within six goals the last time they met in August 2017.
"The Proteas are enormously respected by the Diamonds," Alexander said.
"We expect them to continue to grow, as they did between our two encounters last year. South Africa really challenged us the last time we played in Canberra.
"Although we won by six goals in the end, they led halfway through the game and pushed us right to the final whistle.
"Our athletes came up against and trained alongside Karla Pretorious and Erin Burger in Suncorp Super Netball.
"We know how tough they are and how much they fight to the very end. We have to ensure that we bring our absolute best."
Plummer coached Australia to world titles in 2007 and 2011,
"They (Australia) are the reigning world champions, and it is important for us to be as competitive as possible against them," Plummer said.
"We are steadily closing the gap between us and the two top teams, Australia and New Zealand.