Mollie O'Callaghan (pictured) was one of Australia's standout performers on day two of the Duel in the Pool competition between the US and the Aussies.
Pennington only competed for USC for a semester, and ended up dropping 15 seconds in the 1650 free and winning a Pac-12 title in her time with the Trojans.
Junior Pan Pacs team members Natalie Mannion and Teagan O'Dell are the only swimmers on the women's side of the roster taking on both Jr. and Sr. Nationals.
US Summer Nationals action keeps rolling tonight with finals of the 400 IM, 100 breast, and 100 back, featuring top teens, college stars, and Olympians.