Roger Federer was the defending champion and successfully defended his title , defeating Marin Čilić in the final , 6 -- 2 , 6 -- 7 , 6 -- 3 , 3 -- 6 , 6 -- 1 . It was Federer 's 20th Grand Slam singles title and record - equalling sixth Australian Open men 's singles title ( tied with Roy Emerson and Novak Djokovic ) . With the win , Federer became the first male player to win at least six titles at two Grand Slam tournaments ( six at the Australian Open and eight at Wimbledon ) . Federer became the oldest man to win a Grand Slam singles title in the Open era since Ken Rosewall in 1972 . The time span between Federer 's first Grand slam glory at Wimbledon and this latest , almost 15 years , is an Open era record in the men 's singles field . This was also the 10th time that Federer has defended a Grand Slam title , with the previous time being at the 2008 US Open . Čilić became the first Croatian player to reach a singles final at the Australian Open .

Question: who has won the mens singles title in the australian open tennis tournament
Answer: Roger Federer