World number one survives physical collapse and five hour marathon to keep Grand Slam history bid alive.

A cramping Carlos Alcaraz drew on every physical and mental reserve to claw his way back from the brink and defeat Alexander Zverev, reaching his first Australian Open final after a spellbinding encounter in Melbourne.

The Spanish world number one prevailed 6-4 7-6 (7-5) 6-7 (3-7) 6-7 (4-7) 7-5 after five hours and 27 minutes, although the scoreline only hints at the extraordinary drama that unfolded on Rod Laver Arena.

Alcaraz had taken control by winning the opening two sets and appeared to be cruising when, serving at 4-4 in the third, he suddenly pulled up and began to struggle badly with cramp, barely able to move or serve.

A medical timeout followed, much to the frustration of third seed Zverev, and Alcaraz looked a shadow of himself as the German forced the match into a deciding fifth set.

Zverev seized the initiative by breaking early in the decider and later served for the match at 5-4, but Alcaraz summoned an astonishing revival.

Lifted by the crowd, he broke back to level before capitalising on Zverev’s nerves when the German served at 6-5 down in an attempt to force a 10-point tie-break.

Alcaraz collapsed to the court in disbelief as Zverev pushed a backhand wide, sealing one of the most dramatic victories of his career.

CBI News reports that the win keeps alive the 22-year-old’s bid to make more tennis history. Victory in Sunday’s final would see him become the youngest man to complete the career Grand Slam.

Only Novak Djokovic and Alcaraz’s own physical condition now stand between him and a fourth successive Grand Slam final against Jannik Sinner. Djokovic, chasing a record 25th major singles title, faces world number two Sinner later on Friday.