TORONTO, ON - JULY 28: Stan Wawrinka of Switzerland plays a shot against Jack Sock of the USA during Day 4 of the Rogers Cup at the Aviva Centre on July 28, 2016 in Toronto, Ontario, Canada. (Photo by Vaughn Ridley/Getty Images)
TORONTO, ON - JULY 28: Jack Sock of the USA plays a shot against Stan Wawrinka of Switzerland during Day 4 of the Rogers Cup at the Aviva Centre on July 28, 2016 in Toronto, Ontario, Canada. (Photo by Vaughn Ridley/Getty Images)
TORONTO, ON - JULY 28: Stan Wawrinka of Switzerland plays a shot against Jack Sock of the USA during Day 4 of the Rogers Cup at the Aviva Centre on July 28, 2016 in Toronto, Ontario, Canada. (Photo by Vaughn Ridley/Getty Images)
TORONTO, ON - JULY 28: Stan Wawrinka of Switzerland plays a shot against Jack Sock of the USA during Day 4 of the Rogers Cup at the Aviva Centre on July 28, 2016 in Toronto, Ontario, Canada. (Photo by Vaughn Ridley/Getty Images)
TORONTO, ON - JULY 28: Stan Wawrinka of Switzerland plays a shot against Jack Sock of the USA during Day 4 of the Rogers Cup at the Aviva Centre on July 28, 2016 in Toronto, Ontario, Canada. (Photo by Vaughn Ridley/Getty Images)
