LIVE: Great's dire warning for teenage 'freak'

Australian tennis large Wally Masur is disquieted teenage superstar Carlos Alcaraz volition person constricted petrol successful his vessel for his US Open semi-final clash with Frances Tiafoe.

Alcaraz, 19, played for 5 hours and 15 minutes to bushed Jannik Sinner successful a gruelling five-set thriller that didn't decorativeness until astir 3am successful New York.

About a time and a fractional later, helium volition instrumentality to Arthur Ashe Stadium to look American challenger Tiafoe, who's hoping to outpouring an upset connected the No.3 seed.

Masur - similar many, galore others - was successful awe portion watching Alcaraz spell to enactment against Sinner. His highlights reel included an audacious behind-the-back baseline instrumentality that was followed up by a passing changeable to triumph the point.

"He is simply a freak, this kid," Masur told Stan Sport's Grand Slam Daily.

"He's 19 years of age, moves similar a jack rabbit astir the court, throws himself astatine everything.

"Tennis is successful bully hands. These guys person got it all."

Alcaraz, though, besides played a agelong five-setter successful the 4th circular and has played adjacent to 10 hours of tennis starring into his semi-final against Tiafoe.

Masur tin odor an upset brewing arsenic the American looks to instrumentality vantage of the heaviness successful his teen opponent's legs.

"You've got to retrieve some those guys (Sinner and Alcaraz) had agelong five-setters anterior to this, and Alcaraz finished his erstwhile lucifer astatine 2.30am," Masur said.

"That benignant of workload precocious into the evening, it starts to messiness you up arsenic the tourney goes on.

"Tiafoe is sitting beauteous astatine location watching this going, 'go hard, boys'."