Novak Djokovic was booed off court after his Australian Open semi-final was cut short due to injury, and his Davis Cup captain issued a passionate defense.

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,

Novak Djokovic’s quest for a record 25th grand slam title has been cut short at the Australian Open after he stunningly retired from his semifinal match due to a left leg injury.

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.

Facing Sinner reminded Alexander Zverev of trying to solve the challenge presented by the 24-time major champion Djokovic.

Novak Djokovic has reacted to the crowd at the Australian Open booing after he decided to retire from his semifinal against Alexander Zverev. The Serbian tennis player, 37, had taken to the court with his left leg heavily taped following Tuesday’s injury.

Serbian Davis Cup captain Viktor Troicki has demanded Channel Nine commentator Tony Jones be banned from covering tennis for life following controversial comments about Novak Djokovic at the Australian Open.

Novak Djokovic was forced to retire hurt from the Australian Open semifinals - and the Serbian may not be back in action until the French Open.