The Wiggle-High5 rider, chasing a third victory after also winning the Giro Rose in 2010 and 2013, was simply too good for the rest of the field on the gruelling 10.8 per cent gradient slopes of the Mortirolo.

British veteran Emma Pooley was the only person able to stay with the American before losing touch on the descent.

Abbott crashed on the steep downhill section, but recovered to win in 2hours 40min 23sec.

Elisa Longo Borghini won a sprint for second place after the chasing pack overhauled Pooley.

In a one-two finish for the Wiggle-High5 team, the Italian rider crossed 37 seconds behind her team-mate.

Tatiana Guderzo, another Italian riding for Hitec Products, finished in the same time in taking third place.

Abbott now leads by 10 seconds from Megan Guarnier, who finished fourth today, with Longo Borghini five seconds further adrift in third.

“It has been a crazy stage, as for its difficulty as for my troubles due to a crash in the downhill. 

"But I’m happy to be the new Pink Jersey and this is important."

Tomorrow's sixth stage will see the field tackle a 118.6km route from Andora to the concluding ascent of Madonna della Guardia.

If Abbott can continue her dominant form, she would have ample opportunities to extend her lead.