Tomas Machac, a rising star from the Czech Republic, stunned world no. 2 Carlos Alcaraz with an incredible performance in the Shanghai Masters quarterfinals. With his stunning 7-6 (5), 7-5 victory, the 23-year-old put an end to Alcaraz’s 12-match winning streak and set up an exciting semifinal matchup with Italian phenom Jannik Sinner. Tomas Machac…