Whitnell shot six birdies in his first eight holes and started the following nine at Ullna Golf and Country Club with three more in a row from the 10th hole.
The 10th Birdie of the day on the 15th left the 34-year-old needing to play the last three of the bottom three to score the second 59th in DP World Tour history, but he could only par 16 and 17 before the game. does a birdie on the last.
Whitnell, who hit the eagle’s net from 96 yards with his last shot of the opening day 66 yards, said: “It’s been pretty good today.
“Obviously yesterday was great, I had a little bit of motivation after taking my last shot and I made it today.
“I played well, hit the right shots at the right time, took medicine if I was not in the right position and made a few shots that helped.
“I tried to stay in the present, it’s obviously harder to do than it actually is but I just tried to take it one step at a time and it’s been working fine until today.”
At 17 points below par, Whitnell led Germany’s Ryder Cup hopeful Yannik Paul six times, with Scotland’s Richie Ramsay hitting back again after 66 without a bogey.
England’s Alice Hewson and France’s Emma Grechi were the women’s tennis players who trailed the top five in a unique event that saw 78 men and 78 women compete on the same court for a prize pool and a trophy.
Defending champion Linn Grant, who recorded a stunning nine-game win 12 months ago in Halmstad, added 69 to her opening 72 to lose by three points.