Novak Djokovic was beaten 7-6 (6), 6-3 by big-serving Reilly Opelka in the Brisbane International quarterfinals.

Citing a back injury, American Reilly Opelka retired from the Brisbane International final down 1-4 to Jiri Lehecka.

Djokovic is in search of his 25th Grand Slam title at the Australian Open, but fell short of the semifinals at his warm-up event.

Jiri Lehecka claimed the Brisbane International men's title after Reilly Opelka retired with an injury while trailing 4-1 in the opening set.

Czech Jiri Lehecka has won the Brisbane International after feelgood story Reilly Opelka retired with a back complaint when trailing 4-1 in the final.