Answer
Yes, Sofia Arvidsson did defeat Sam Stosur in the quarterfinals of the 2006 Nordea Nordic Light Open with a score of 7-5, 3-6, 7-5 in a thrilling three-set match. Arvidsson, ranked 84th in the world at the time, upset the higher-ranked Stosur, who was ranked 24th, to advance to the semifinals of the tournament.