Kyrgios takes dig at Wawrinka's girlfriend during Rogers Cup match

Nick Kyrgios has established himself as a brash up-and-comer on the ATP tour, but the 20-year-old Australian may have taken things too far in his second-round match against Stan Wawrinka at Canada's Rogers Cup.

At one point during the contest, Kyrgios could be heard issuing a verbal low-blow about fellow Australian Thanasi Kokkinakis and Wawrinka's girlfriend.

Wawrinka retired in the third set due to injury, and Kyrgios said afterwards that he got caught up in the moment after Wawrinka had been "lippy" with him during the match.