John Isner nails a 146 mph ace at the US Men’s Clay Court Championship in Houston, which is said to be the fastest serve ever fired at the historic River Oaks Country Club. Isner hit a 149 mph serve at the 2011 Cincinnati Masters event. Ivo Karlovic owns the fastest recorded serve at 156 mph, but he hit that blast during a Davis Cup tie, which is an ITF event. Milos Raonic hit the second fastest serve at 155.3 mph at the 2012 Rogers Cup.
"I did?" Isner asked the Houston Chronicle when informed of the River Oaks record. "Wow. I'm feeling pretty good. Nothing is bothering me, and that's a good sign. I feel like I'm doing the right things to give myself these opportunities. It's encouraging."