Roger Federer was given a point penalty as he followed Novak Djokovic out of the Shanghai Masters quarter-finals in a bad-tempered defeat to Alexander Zverev on Friday.
The 22-year-old German won 6-3, 6-7 (7/9), 6-3 as the Swiss legend Federer was penalised after twice hitting the ball out the court in anger.
The sixth-ranked Zverev faces Austria's Dominic Thiem or Matteo Berrettini of Italy in the semi-finals on Saturday.
The 20-time Grand Slam champion Federer saved five match points to force a deciding set, but he then became engaged in a continual war of words with the umpire.
The 38-year-old's trademark cool evaded him as the new generation of men's tennis stars took centre stage in Shanghai.
His point deduction came at 3-0 and 30-15 down in the third set, as he threatened to unravel.
Earlier Friday, the 21-year-old Stefanos Tsitsipas stunned world number one and reigning champion Djokovic 3-6, 7-5, 6-3.
Tsitsipas plays another young talent, the 23-year-old Russian Daniil Medvedev, in the last four.