The house, with a CV of $920,000, went for $1.15 million, with five pre-auction offers even before the bidding opened.
Ray White's Megan Jaffe brought forward an auction by two weeks.
She said the two-bedroom unit in Remuera's popular Victoria Ave had a pre-auction offer of $685,000 but sold for $902,000.
She admitted the move was not popular. "Buyers don't like it because they're often still doing due diligence and taking their time. No one likes it but we work for the vendor, not the buyer," she said, adding that faster auctions put more pressure on buyers and often resulted in a better price.
Ms Jaffe also said the hot market was resulting in many houses being sold but never advertised on the open market "and it's appalling, it's very common. Sales people come up to your door and say they've got a buyer and it's a good price. But I don't do this and I don't advise people to do it."
Few people would admit to using these tactics, she said, although many Remuera houses were being sold like this.
Another property in Remuera - a four-bedroom home - had an opening bid of $1,285,000 and sold for $1,430,000 with seven bidders after the auction was brought forward.
Barfoot & Thompson chief executive Wendy Alexander said one open home was held and everyone was advised about hurrying up the auction because of a pre-offer.
One buyer, who did not want to be identified, criticised agents for cheerleading rising house prices, adding fuel to the fire and damaging New Zealand "because agents were a contributing factor to rising house prices which is ruining the country".
"Each dollar we spend on our mortgage is sent straight overseas," he said, "taking money out of our consumer market and out of New Zealand."
Here's a look at some of the recent surprising house sales:
* $1m 'entry level' house sign of times
* Mt Albert house fetches $400k above valuation
* House bought last year for $590k - sold this year for $846k
* Half a shoebox - for $45,000
* Do-up delight: $1.3m state house
* Do-up sells for $2m in three days
* Solid but modest former state house sells for $1.45m