Reilly Opelka books semi-final collision course with Nick Kyrgios

The giant American, who measures in at six-foot-11, was terrific in the opening set, winning 84 per cent of his successful first serves (16-19) and allowing no break point opportunities.

The second set was much more competitive, as Brouwer broke first to go up 3-1, but Opelka answered instantly and then grabbed the match-winning break when 6-5 up to avoid a tie-breaker.

Opelka will face a fresh Nick Kyrgios in the semi-final after the Australian was gifted a walkover win against Michael Mmoh due to injury.

In a clash between two top-five seeds, world number 29 Christian Garin got the better of world number 13 Taylor Fritz 6-2 6-7 (5-7) 6-3.

What made Garin successful in the first and third sets was his return game, winning more than half of his return points in those sets combined (26-51).

Almost 3 hours later, @Garin_Cris takes the world No. 13 6-2, 6-7, 6-3 to secure his place in the semifinals @mensclaycourt | #USClay pic.twitter.com/BfcjpXxEHU

— ATP Tour (@atptour) April 8, 2022

Fritz had chances to get back into the game, but Garin saved 11 of 14 break point opportunities, including six of seven in the deciding third set.

Garin will play American John Isner in the semi-final after Isner triumphed in a three-set battle against Frances Tiafoe 6-4 2-6 6-3.

Isner's trademark serve was inconsistent, and abandoned him in a grim second-set performance, winning just 11 of 21 service points on his way to getting broken twice to allow Tiafoe to force the match into a third frame.