The defeat ends the Diamonds 21-game winning streak and relegates the Australians to second place in Pool A as the Netball World Cup progresses to the Qualification Round, commencing on Tuesday.
“Full credit to the Silver Ferns, they put out a really great performance today and a little bit of a different performance to what we traditionally expect of them,” Geitz said in the post-match press conference.
“We just weren’t quick enough to adjust and there were a lot of uncharacteristic things we did out on court which is the most disappointing part.
“I think we were our own worst enemy out there at times.”
A pragmatic Geitz said the defeat would be a good lesson for the Australians as they prepare for their next three games with a spot in next weekend’s finals on the line.
“It’s disappointing but I think it’s a good thing for the group to experience early on (in the tournament),” Geitz said.
“If we don’t play to the standards we set that’s exactly what happens and that was a really good reality check for all of us.”
The Diamonds trailed by as many as eight late in the third quarter but the introduction of Erin Bell at goal attack and Paige Hadley, making her first appearance against the Silver Ferns, sparked life into the side.
The Australians pegged the score back to three goals with four minutes remaining in the match to the delight of the world record crowd of 16,233 but costly errors late handed the match to the Silver Ferns.
“I think games like this are an important part of the progress of the team with some different combinations working out on court,” Geitz said.
“At least now we’ve got some material to work off and just look at what didn’t work and what did work.”
Diamonds coach Lisa Alexander said the rest day on Monday would provide an opportunity to reassess before the qualification stage.
“(Our volumes at goal) were nowhere near, we didn’t have enough and we provided too much ball for our defenders to try and stop,” Alexander said.
“We need to really work on our full court defence which was uncharacteristically not there today.
“There’s no doubt that we have to look deeply over the next 24 hours at ourselves, which includes the coaching staff, and we’re going to do that.
“We’ve always said this tournament is long and hard and the next three games are extremely important to put in a good mental and physical frame for the weekend.”
The Australian Diamonds next game will be on day five (Tuesday) of Netball World Cup SYDNEY 2015 – with its opponent still to be confirmed – at Allphones Arena, Sydney, at 8.20pm (AEST).
Don’t miss a minute of action with the game to be broadcast live on FOX SPORTS, Network Ten, Netball Live app, available to download from the App Store and Google Play, and on ABC Grandstand. Check your local guides for match details.