Dominic Thiem advances to third round after Denis Istomin retirement

Dominic Thiem has booked his place in the third round of the US Open after Denis Istomin retired injured in the third set.

The Austrian was two sets up when his opponent retired, having held serve throughout the first set to win 6-4.

He repeated the feat in set two, breaking Istomin in game nine to double his lead.

Istomin retired after losing his serve in the first game of the third set.