Melbourne: Unseeded Russian Anastasia Pavlyuchenkova won a marathon three-setter against American fifth seed Sloane Stephens 6-7(3) 6-3 6-3 to reach the Australian Open quarter-finals.

The Russian reached her second quarter-final at Melbourne Park after her 2017 run and will now meet another American in Danielle Collins for a place in the last four.

Stephens, the 2017 US Open winner, started strongly by gaining a 4-1 advantage but her Russian opponent got the break back before the 25-year-old American won the set via a tiebreaker.

The second set started in similar fashion with Stephens breaking early to run up a 2-0 lead before another fightback from the 27-year-old Pavlyuchenkova.