Defending Australian Open champion Novak Djokovic won his longest first-round Grand Slam match after being tested by qualifier Dino Prizmic.
The Serb, chasing a record-extending 11th men's title, needed four hours and one minute to beat the 18-year-old Croat 6-2 6-7 (5-7) 6-3 6-4.
Prizmic, playing in his first Grand Slam match, saved six match points before Djokovic secured victory.
"He gave me a run for my money," Djokovic said in an on-court interview.
The 36-year-old, who is aiming for a record 25th Grand Slam singles title, will face Alexei Popyrin or Marc Polmans in the second round.