John Millman’s giant-killing run at the Delray Beach Open has come to a frustrating but somewhat apt ending at the hands of men’s tennis’s physical giant.

American beanpole Reilly Opelka needed three tiebreakers and exactly three hours to deny Millman 7-6 (10-8) 6-7 (3-7) 7-6 (7-4) in a midnight epic.

At 211cm, or 6 foot 11 inches in the old scale, Opelka is the equal-tallest player along with Ivo Karlovic in the history of the ATP Tour.

And, try as he might, the American proved too tall an order for Millman.

In a match dictated by serving, Opelka crunched 16 aces to Millman’s three.

Both players dropped only one of their 18 service games, forcing the three tiebreakers, but Millman had to fend off nine break points while Opelka was far more comfortable, needing to save only one.

The loss was Millman’s first in four meetings with Opelka, the world No.20 and second seed at Delray Beach.

Still, after beating fellow seeds Grigor Dimitrov, Maxime Cressy and American Marcus Giron to reach the final four, Millman is set to climb from 91st to 80th in the rankings on Monday.

Opelka will meet top-seeded Englishman Cameron Norrie in the final.

Norrie beat fourth-seeded American Tommy Paul 6-3 6-3 in his semi-final.

It is be the first time in the tournament’s 30-year history that the No.1 and No.2s will clash for the title.