Thompson's 66 was her third round of 67 or better in the tournament and moved her to 17-under 196 after 54 holes. Ilhee Lee, the leader after each of the first two rounds, turned in a 1-under 70 for the third round and is in second at 14-under.
Suzann Pettersen, who also didn't commit a bogey Saturday, shot 67 and is tied with Feng Shanshan, whose third-round 70 included two birdies, for third at 11-under.
The tournament was halted for about an hour Saturday because of lightning.
Lee lost her one-stroke overnight lead with a bogey at the second hole and Thompson, with three birdies over Nos. 4-7 built a lead. Thompson had back-to-back birdies at the sixth and seventh holes right after play resumed following the lightning storm.
Lee slipped back with a bogey at the ninth -- only her third of the tournament -- and Thompson pushed her advantage with birdies at 10 and 12. Lee also had a birdie at 12 and stayed within three strokes with a closing birdie.
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