Dubai, United Arab Emirates (My Sportsbook) - Two-time defending champion Annika Sorenstam opened with a two-under 70 on Thursday and trails first-round leader Johanna Head by four strokes at the Dubai Masters.

Sorenstam, who is stepping away from the game after this event, is tied for sixth place with 10 other players.

Head opened with a six-under 66 and is two strokes clear of Anja Monke, who won the Open de France Dames the final week of September.

Veronica Zorzi, Maria Boden and Katharina Schallenberg share third place at three-under 69.

Sorenstam played the back nine first at Emirates Golf Club. She ran off three birdies in her first four holes, but stumbled to a bogey on the par-four 14th.

She atoned for that mistake with a birdie at 16, but stumbled to a double- bogey on the par-five 18th after spinning her third shot into the water.

Sorenstam birdied three of the first five holes on the front side to climb to four-under. However, she closed with back-to-back bogeys to share sixth place.

Head got her round going with birdies on the second and fourth. She moved to three-under with a birdie on the seventh and carded her fourth birdie on the 10th.

After five straight pars, Head birdied two of the last three holes to secure the first-round lead and close out a bogey-free round.

Sorenstam shares sixth place with Carmen Alonso, Iben Tinning, Laura Davies, Sophie Giquel, Felicity Johnson, Emma Cabrera-Bello, Nina Reis, Virginie Lagoutte-Clement, Trish Johnson and Ashleigh Simon.