MELBOURNE, Australia — Of all the praise bestowed on Jannik Sinner after he won his second consecutive Australian Open championship, and third Grand Slam title overall, nothing felt as significant as the comparison made by runner-up Alexander Zverev .

Novak Djokovic has retired from his Australian Open semifinal against Alexander Zverev after losing the first set in a tiebreak. Djokovic missed a regulation putaway volley on top of the net down 5-6,

Zverev will face defending Australian Open champion and No. 1 seed Jannik Sinner, who beat American Ben Shelton 7-6 (2), 6-2, 6-2, in Sunday's final. Zverev is pursuing his first major tournament title.