World champion Sally Pearson timed a season's best of 12.39sec to advance smoothly into the final of the women's Olympic 100m hurdles alongside US rivals Dawn Harper and Kellie Wells.
The 25-year-old Australian managed to safely negotiate the 10 hurdles, unlike Chinese 2004 Olympic champion Liu Xiang in the men's 110m hurdles earlier in the day.
Pearson will be joined in the final by second-placed Canadian heptathlete Jessica Zelinka, and defending Olympic champion Harper of the United States.
The American clocked a personal best of 12.46 in winning her heat from Austrian Beate Schrott (12.83sec).
Harper's teammate Wells, the only hurdler to have beaten Pearson this season, also qualified as a heat winner in 12.51sec.
Turkey's two-time European champion Nevin Yanit was second in Wells' heat in 12.58sec.
The other two qualifiers for the final were a third American in Lolo Jones and Canadian Phylicia George, with US-born British hope Tiffany Porter missing out after clocking 12.79sec when finishing fourth in Pearson's heat.