Germany's Anja Monke grabbed the lead with a four-under-par 68 on the Majlis Course.
Starting the day three shots behind Sorenstam, Monke carded three birdies over the front nine to reach the turn in 32.
She double-bogeyed the par-three 11th but came back with birdies on the 13th, 16th and 18th.
Monke is nine under par, two ahead of Italian Veronica Zorzi and Denmark's Iben Tinning.
Zorzi had been the outright leader on nine under after 14 holes but was given a two-shot penalty after it was spotted that her ball had moved at address before she putted on the 15th green.
Sweden's Sophie Gustafson shares fourth place with England's Laura Davies on six under.
Sorenstam began the day with a one-stroke lead but struggled to a 75 to end the day four off the lead in a share of sixth.
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