Jack Sock feathers a beauty on Day 7 of the U.S. Open
A dangerous moment on the Grandstand happens during doubles.
Nick Kyrgios' shotmaking wizardry was on display early in his match with Ilya Marchenko.
The 2015 finalist reaches quarterfinals for fourth time in last five years.
Novak Djokovic and Rafael Nadal are back in action on Day 7 of the U.S. Open. Keep up with all the action in the Tennis Now Live Blog.
"The mentality that he's shown really has been the most impressive part," says Murray.
The Swiss did not win this set, but he eventually gutted out a five-set wins.
