Montreal: Nick Kyrgios was jeered by some supporters as he crashed out of the Rogers Cup on the day he apologised and was fined for his jibe towards Stan Wawrinka.

It was an eventful 24 hours for the World No 41, whose victory over Wawrinka in Montreal on Wednesday was overshadowed after it had emerged Kyrgios had sledged the Swiss.

Australia’s Nick Kyrgios during his Rogers Cup match against USA’s John Isner on Thursday. PIC/AFP

On-court microphones recorded 20-year-old Kyrgios walking to the net and saying: ‘”Kokkinakis banged your girlfriend. Sorry to tell you that mate” - an apparent reference to Australian Davis Cup teammate Thanasi Kokkinakis.

Teenage Croatian player Donna Vekic has been linked to Wawrinka since he divorced his wife Ilham in April. Vekic, 19, was in the crowd to watch the Swiss’ Wimbledon third-round win over Fernando Verdasco last month.

Kyrgios has been hit with an initial fine of 10,000 US dollars — equating to £6,405 — but that could rise, said a spokesman for men’s tour the ATP.

French Open champion Wawrinka branded the behaviour of Kyrgios 'unacceptable', while World No 1 Novak Djokovic said the comments were 'completely unnecessary'.

Kyrgios offered an apology on Thursday, and he was later beaten in straight sets by John Isner in their third-round match.

Kyrgios was booed as he emerged onto the Banque Nationale court and received similar opprobrium as he exited the stadium after a 7-5, 6-3 defeat to the big-serving American.