Ouch. What a look on her face. To Lexi's credit she immediately counted the stroke, but that smile is the smile of a golfer who feels very embarrassed about what just happened.
The whiff happened on the ninth hole and it meant a double-bogey for Thompson. She wound up shooting 71.
Hopefully Lexi's whiff won't come back to haunt her the way one of the most infamous whiffed putts in golf history did Hale Irwin at the 1983 British Open. Irwin whiffed a 2-inch putt in the third round ... then finished one stroke out of a playoff.
Just in case the Golf Channel video above doesn't work for you, here's an Instagram capture of Lexi's whiff:
Poor @Lexi, having bad day misses 1/2" putt. #whyyouputteverythingout