Jannik Sinner played his 50th match as number one to win the title in Melbourne, beating Alexander Zverev in the final.
Sinner boasts the best number one winning percentage following the victory, which represents his third career Grand Slam title.
Winning her first meanwhile was Madison Keys, who defeated world number one Aryna Sabalenka to lift the Australian Open trophy.
Keys lost the 2017 US Open final to Sloane Stephens in her first Grand Slam final, but recovered in Melbourne to deny Sabalenka a third successive Australian Open title.