Unseeded Russian Karen Khachanov advances to US Open semifinals after hobbled No. 28 seed Alexander Blockx retires in third set

Alexander Blockx tried to give it a go.

But the 28th-seeded Belgian was too hobbled to finish Wednesday with a trip to the US Open semifinals at stake.

Blockx retired in the third set against unseeded Russian Karen Khachanov , while trailing 6-2, 7-5, 3-2, unable to continue with a rib injury that had hobbled him since the Round of 16. The injury bothered Blockx throughout the match. 

He visibly struggled with his serve in the first set, where he was broken twice. He took a medical timeout between sets to have work done not on his ribs, but his left foot.

He remained on serve in the second set until Khachanov broke him late to serve for the set, 7-5. Blockx then took another medical timeout, this time to have work done on his torso.

He was in visible pain in the thid set and opted to retire when Khachanov broke him again to take a 3-2 lead. Khachanov advances to face the winner of Wednesday’s prime-time match between No. 1 seed Alexander Zverev and unseeded Botic Van De Zandschulp.

This story will be updated.