American teenager Caroline Marks had already served notice in Round 3, shredding her way into the quarterfinals on the women's side of Surfing's Olympic debut with the highest score of the day on the final day of prelims.

During Tuesday's quarters at Tsurigasaki Surfing Beach, Marks, 19, was nearly as sharp. So was her 28-year-old teammate, Carissa Moore, and as a result, Team USA guaranteed itself a spot on the sport's first Olympic podium.

Marks, who posted a score of 15.33 in Round 3, overwhelmed Costa Rica's Brisa Hennessy, 12.50-6.8, while Moore was similarly dominant in dispatching Brazil's Silvana Lima, 14.26-8.30, to advance to the semis as well.