The Flight Stakes was considered a two-horse race between Hungry Heart and Dame Giselle but the David Payne-trained Montefilia has spoiled the party.
The star fillies dominated betting with Hungry Heart sent out a $1.90 favourite and Dame Giselle at $2.80 the only other runner at single-figure odds.
Hungry Heart looked like she would give James McDonald a dream start to the day after he had ridden the first four winners when she loomed topping the famous Randwick rise.
But she was pegged back in the final stride by Hugh Bowman and Montefilia, who edged her out by a half-neck.
Payne initially had Victorian Oaks plans for Montefilia and while that race is still an option, he is leaning towards keeping her in Sydney for the Group One Spring Champion Stakes next Saturday.
"Depending on how she pulls up we will back her up next week. Then she will go to the paddock," Payne said
"She's a laid-back filly, she eats well, so she won't have to do too much this week. We'll just see how she is in the next few days.
"The Oaks is still on the cards if she doesn't do well in the week."
A champion jockey and trainer in South Africa, Payne now trains a boutique team at Rosehill and was thrilled to land a major on one of the biggest days of the Sydney spring.
"We've only got about 16 in training but a small string suits me now," Payne said.
"I've done all that I've wanted to do, I just love winning big races.
"We knew she had improved and we knew the mile would suit her."
Vangelic led and did a good job to hold on for third another two lengths away.
Chasing a clean sweep of the Princess Series following wins in the Silver Shadow, Furious and Tea Rose Stakes, Dame Giselle was locked up on the fence in the straight but didn't lengthen once clear to finish fourth.