Twenty-one of the 32 matches were completed before play was halted by darkness.
Fernandez Valdes, who led the stroke play portion with a 36-hole total of 5-under-par 139, needed to make a 25-foot birdie putt on the first extra hole to advance over Cory McElyea. Neither player held more than a one-hole margin.
I knew I was going to win, said Fernandez Valdes in his limited English. I had no more legs. I was tired. I couldnt make putts like before. It was amazing.
Dom Bozzelli won the fourth and fifth holes and slowly pulled away to earn a 4-and-3 victory over Whitsett, who was seeking to become the first player to win consecutive titles since Tiger Woods did it in 1992-93.
Bobby Wyatt and Patrick Rodgers each earned one-sided victories.
Wyatt never lost a hole against Drew Preston on his way to a 6-and-5 decision. Rodgers beat Parker Clowers by the same score.
I felt comfortable with my lead after the 11th hole, said Wyatt, who blasted from a greenside bunker and made a 35-footer for birdie to go 5 up.
Tom Lovelady celebrated his 15th birthday with a big victory over Dashiell Lindsell, 6 and 5.
I wont forget this day. Its one of the best days Ive ever had, Lovelady said. First, I made it to match play and then I won 6 and 5.
Another favorite is Julian Suri, who won his first match over Richard Lamb, 5 and 4. He narrowly lost in a nine-hole playoff for the last spot in his U.S. Open sectional qualifier earlier this summer.
He made some mistakes and took the pressure off of me, Suri said.
Michael McGowan, a 2007 quarterfinalist, is the lone fully exempt player to stay alive for the moment. He and Bobby Patel are deadlocked after 21 holes. Theyll be back to continue their match Thursday morning, starting on the 464-yard 4th hole.