Australian gold medal hope Sally Pearson set the fastest time in qualifying for the semi-finals of the Olympic women's 100m hurdles.
The world number one won her heat in 12.57 seconds to set the early pace before Tuesday night's final.
Americans Lolo Jones, Kellie Wells and Dawn Harper, the defending champion, eased through along with Great Britain's Tiffany Porter.
"Tomorrow is another day and I'll see what I can do," Pearson told BBC Sport.
"I was really quite nervous for that race and now I can go back and fix my body for tomorrow."
Pearson, the reigning world champion, is one of the hottest favourites at the Olympic Stadium.
After disappointing performances from their swimmers and cyclists, Australia have won just two gold medals - a relay gold in the pool for 4x100m freestyle women and an individual gold for sailor Tom Slingsby in the Laser class.
Asked about the pressure on her to add to the total, Pearson said: "Well, there's nothing I can do about it now. There's more work to do."
Pearson's build-up to the London Games was affected by a surprise loss to Wells at the Diamond League meeting at Crystal Palace nearly three weeks ago.
Wells was also in good form on Monday, winning the third heat in 12.69secs.
Jones, who was favourite for the 2008 Olympic title before she clipped a hurdle in the final, was the second fastest qualifier in 12.68.
Britain's Porter went through in 12.79 and said: "I'm looking forward to the semis. I was really nervous. I haven't slept much but I'm glad it's over and now I can move forward."