Radwanska surprises number one Halep

The Pole, who won in Miami in 2012, had not posted back to back victories since January.

Halep's loss was the second consecutive tournament in which the Romanian had not made it to the final. She was eliminated in the semi-finals at Indian Wells last week, losing 6-3 6-0 to eventual champion Naomi Osaka of Japan.

Fifth seeded Czech Karolina Pliskova also had a tough time before battling past Taiwan's Hsieh Su-Wei 6-4 1-6 7-6(4).

Pliskova, a former world number one, finally closed out the third-set tiebreak by converting her seventh match point.

Hsieh did not go easily. The doubles specialist, who made it to the last 16 in the Australian Open, earned a break point to make it 5-5 in the first set before Pliskova prevailed.

Hsieh dominated the second set as Pliskova made 12 errors.

The Czech broke at 5-3 in the third set before Hsieh saved three match points to break back. Pliskova came close again to winning the match but Hsieh held to send the players to a tiebreak. However, that was as far as her luck ran.