She's done it. Megan Whitehead broke the solo women's nine-hours strongwool lamb shearing record of 648 with less than 10 minutes to go.

The 24-year-old Gore shearer began her attempt early this morning at the Grant Brothers' Gore woolshed, getting through 153 sheep in the first run and 132 in the second, putting her 16 ahead of the record at the morning smoko break. In the third and fourth sessions she sheared 126 and 125 respectively. Whitehead finished with a new record of 661 sheep.

Previous record holder Emily Welch sheared 144 sheep in her first run, 125 in the second, 123 in the third and 127 in the fourth in 2007 when she set the solo women's nine-hours strongwool lamb shearing record of 648 (72 an hour). The previous record of 541 had been set in 1989.

Megan Whitehead, left, with previous record holder Emily Welch. Photo / Rowena Duncum

Whitehead, a daughter of former shearers Quentin Whitehead and Tina McColl, is already the joint holder of one world record, the four-stand eight-hours women's record of 2066 lambs set in the Central North Island on January 23 last year. She shore a personal best of 608, the best of the day and at an average of 76 an hour.

Under the auspices of the World Sheep Shearing Records Society, there are standard rules, with five "runs" during the day, from 5am-7am, 8am-9.45am, 10.15am-noon, 1pm-2.45pm, and 3.15pm-5pm, separated by one-hour breakfast and lunch breaks, and half-hour morning and afternoon "smoko" (morning and afternoon-tea breaks).

Starting the day at 5am and needing an average of at least 72 an hour to break the record, Whitehead had reached the two-third stage of six hours mid-afternoon with 447 down the porthole and heading for a final tally of about 670.

At the afternoon tea break at 2.45pm, the 24-year-old had sheared 546, needing just 99 in the last 1 hour and 45 minutes to break Welch's record, said Doug Laing, of Shearing Sports New Zealand.

Welch flew south today to watch a new piece of history unfold. She had shorn 519 at the equivalent stage of her record.

Live-streaming of the event shows the 60kg Whitehead in athletic form as she handled the lambs which weighed 34-36kg each in a rate of under 50 seconds.

Whitehead had shorn 153 in the first two hours to breakfast and successive 1hr 45min runs of 132, 126 and 125.

The new world record set by Megan Whitehead is 661 sheep. Photo / Rowena Duncum

A large crew was helping around the shed, including her father Quentin Whitehead, monitoring the clock near his daughter's side, and Southand shearing legend and multiple New Zealand representative Nathan Stratford, who was looking after her gear.

At home near Te Kuiti and watching via live-streaming, Sir David Fagan, who 36 years ago was the first to do over 700 in a men's attempt on a nine-hour lambs record under the modern rules, said he was astounded.

"She's going to break it. And if anyone's going to break it again - it'll be her."

The judges - one watching from Australia via AVL – yesterday afternoon gave the green light for the attempt to go ahead when a sample shear of 20 lambs produced 21kg of wool, comfortably over the required minimum of 0.9kg per lamb.