Melbourne, Jan. 30 -- World No 3 Alexander Zverev erupted in anger during a marathon Australian Open semifinal against World No 1 Carlos Alcaraz, accusing the tour of "protecting" the top stars after the Spaniard took a controversial medical timeout.

The drama unfolded in the third set of the five-hour epic at the Melbourne Park courts. Zverev, having stormed to a two-set lead, seemed poised to serve for the match, only for Alcaraz to rally from physical distress, eventually claiming victory 6-4, 7-6 (7-5), 6-7 (3-7), 6-7 (4-7), 7-5 in the longest Australian Open semifinal in history.

The spark for Zverev's fury came when Alcaraz appeared to struggle with cramping in the sweltering Melbourne heat. After a point at 4-4 in the third set, Al...