Stage four of the seven-stage race saw North Shore racer Taylor Gunman conquer the 187km from Te Anau to the peak first in 4hr 45min 19sec.
Sam Lindsay finished second, overtaken in the final 500m, and James Oram was third across the line, meaning he will stay in the yellow jersey for the third consecutive day.
The whole Coronet climb, Gunman said after the race, was tough, as was the section before it.
''That had me going backwards and we hadn't even started climbing.''
To prepare for the race, Gunman had been spending ''too much time on the bike''.
''We treat it as a full-time job. It's a full-time job to do something like this.''
And when the job gets tough, there is no room to think about anything other than survival on a bike.
Gunman said when cycling distances such those involved in the tour, ''you can't think [when racing] - the only thing going through your head is eat, drink, eat, drink''.
Stage three was won by Matt Zenovich and Gunman is conscious ''it's not over until you reach the final finish line - you always have to be thinking a day ahead''.
Coronet Peak last featured in the race in 1981 as an individual time trial, race director Bruce Ross recalled yesterday.
He said that over the past few years, riders had asked for a climb such as Coronet Peak to be introduced into the race.
''It's a hard climb, it's defining, and the riders attacked it with caution.
''We're pretty keen to run it again. It's a welcome addition to the tour. It's the longest climb we have ever had on the Tour of Southland.''
The race doubles as family bonding for Dunedin property valuer Joe Chapman, who is racing his 12th Tour of Southland.
Within his Creation Signs L&M Group Racing team this year is brother Tim.
Team member Grayson Napier, of Nelson, is defending the King of the Mountain jersey.
Fine weather was not what Joe Chapman was expecting and he was expecting the race to be slightly harder because of it.
And as for Coronet Peak, ''there's no flukes coming up this hill''.
Tour of Southland: Today's stage
Stage five (167km) starts at the Invercargill velodrome, heading through Wallacetown, Otautau, Ohai, Nightcaps and Mossburn before finishing in Lumsden.
