After holding their own for much of the opening Constellation Cup game on Friday night, the Silver Ferns slipped, losing the fourth quarter 24-11 to allow a 69-52 blowout in favour of the Diamonds.
The Silver Ferns stood strong in the opening quarter to level 13-13 at the break.
They held on to trail 30-28 at halftime and 45-41 at the third-quarter break, but crumbled in the fourth when the Diamonds put their foot down.
The physicality was always going to be a step up, but Burger acknowledged it was their mental game that let them down the most.
"We just need to mentally be able to take [the physical hits] as well," Burger said.
"I think that’s potentially where the fourth quarter sort of let us down a little bit and letting the moment win that moment, rather than us winning the moment."
They will need to rectify those woes before their second clash in Sydney on Wednesday night.
If the Diamonds win, the Silver Ferns will have to win the final two games if they are to have a chance of retaining the Constellation Cup.
"Personally, I feel like there’s a balance between understanding that that wasn’t good enough in terms of the last quarter.
"We need to have that mentally in a high performance sport, but also acknowledging the three quarters that we did play really good netball ... looking at the three quarters that worked really well and making sure that we continue doing that for four quarters.
"In terms of that last quarter, just making sure that we’re mentally preparing ourselves for the next one because we don’t want to go to New Zealand thinking we could have had that Sydney game.
"We want to make sure we take every game for what it is."
Interim Silver Ferns coach Yvette McCausland-Durie agreed with Burger.
"Certainly competitive for the first three [quarters] and minutes of the fourth, but obviously that difference in the end was pretty significant," McCausland-Durie said.
She acknowledged there were several players in different positions, including Martina Salmon at goal attack.
She was solid for much of the game, shooting 12 of her 15 attempts.
"There’s lots of growth and lots of learnings," McCausland-Durie said.
"I thought defensively we got some ball — yes, there’s more to have — but certainly did get a bit of ball and Grace [Nweke] was a continued threat in the post."
They need to shut down Diamonds shooter Sophie Garbin, who dominated with 43 from 46 attempts.
Constellation Cup
The scores
Australian Diamonds 69
Sophie Garbin 43/46, Kiera Austin 26/31
Silver Ferns 52
Grace Nweke 37/41, Martina Salmon 12/15, Amelia Walmsley 3/4
Quarter scores: 13-13, 30-28, 45-41.
