MARBELLA, Spain (Reuters) - Top seed Victoria Azarenka pulled out of the Andalucia Open at the quarter-final stage with a thigh muscle injury on Friday.

The Belarusian was 4-0 up in the first set against Spain's Maria Jose Martinez when she pulled up in pain. She had treatment courtside but was unable to continue.

Fifth seed Martinez progressed to Saturday's semi-finals where she will meet another Spaniard Carla Suarez, who beat Germany's Tatjana Malek 4-6 6-1 6-2.

Italian second seed Flavia Pennetta saw off Romania's Simona Halep 6-4 7-6 and will next face compatriot Sara Errani, who beat Beatriz Garcia 6-7 6-4 6-3.

(Writing by Mark Elkington, editing by Alison Wildey)