MELBOURNE (AFP) - Women's fourth seed Simona Halep was dumped from the Australian Open at the first hurdle for the second successive year on Monday, having no answer to the power of American Shelby Rogers.

The out-of-sorts Romanian, who called for medical attention after losing the first set, went down 6-3, 6-1 on Day 1.

It was a case of deja vu for the right-hander, who was sent packing at the same stage last year by Chinese qualifier Zhang Shuai.

Halep is one of the fastest movers on court but she was missing her usual zip against the 24-year-old American, who reached the French Open quarter-finals last year.

Rogers' reward is a second-round clash against either Australian qualifier Ashleigh Barty or Germany's Annika Beck.

Big-hitting Spaniard Garbine Muguruza struggled with injury as she battled into the second round with a straight-sets win over New Zealand's Marina Erakovic.

The French Open champion, seeded seventh, needed a medical time-out after the first set for what appeared to be a foot problem before returning to win 7-5, 6-4.