Agnieszka Radwanska blew the Miami Open draw wide open with a stunning victory over top seed and world number one Simona Halep.

Halep was out of sorts in Saturday's third-round match as she followed Caroline Wozniacki in making a surprise early exit from the WTA Premier Mandatory event.

The world number one had looked on course for a comfortable victory over her old adversary when she took the opening set in 34 minutes.

However, her levels dropped dramatically in the second set as Radwanska levelled with aplomb, the Pole finding great spirit to stifle the top seed.

And that continued in the decider as Radwanska forced errors from her rival to come from a set down to secure a 3-6 6-2 6-3 victory and move 6-5 ahead in her head-to-head encounters with Halep.

Halep's forehand was working with pinpoint accuracy in the opener as she dominated from the baseline, not allowing Radwanska's fondness of the slice to stop her momentum.

A strong first serve was returned to the net as Halep moved ahead, but her momentum disappeared and Radwanska raced into 4-0 lead in the second set.

That seemed to jolt the tournament favourite back into action but it came too late to avoid a decider, another Halep error seeing a simple shot fail to clear the net.

Halep's groundstrokes regained their accuracy early in the third – much to the relief of the Romanian – but Radwanska was not going down without a fight.

Having saved a break chance in the sixth game, Halep could not do the same two games later to hand Radwanska the chance to serve for the match.

And she promptly did so as Halep first fired into the net, and then long, to slip to only a third defeat of 2018.