Novak Djokovic was booed off court by some Australian Open fans after retiring injured from his semi-final against Alexander Zverev.
Djokovic, who was bidding for a record-extending 11th title, quit after losing the first set 7-6 (7-5).
The 37-year-old Serb had his upper left leg heavily taped after injuring it in Tuesday's quarter-final win over Carlos Alcaraz.
After he slapped a volley into the net on set point, Djokovic immediately approached the net and shook hands with Zverev.
He waved to the crowd and gave them a double thumbs up, despite audible boos from some sections inside Rod Laver Arena.