Ben Shelton reached his first Australian Open semi-final with a battling win over Lorenzo Sonego that took just under four hours.

The big-serving American won 6-4 7-5 4-6 7-6 (7-4) and will face either defending champion Jannik Sinner or home hope Alex de Minaur for a place in the Melbourne final.

Shelton, 22, eased into a two-seat lead on Rod Laver Arena but dropped his level enough to allow Italy’s Sonego to force a fourth set.

The two were well-matched in the set, with both playing some entertaining points before Shelton’s strong serving helped him pull away in the resulting tie-break.

Shelton, who clocked a tournament joint-fastest 144mph serve during the match, said he was “relieved” to have gotten through.

“Shout-out to Lorenzo because that was some ridiculous tennis,” Shelton added after a quarter-final lasting three hours and 50 minutes.

Both players have benefited from a quarter of the draw which has been left wide open following the early exits of top-10 seeds Taylor Fritz, Daniil Medvedev and Andrey Rublev.

Friday’s semi-final will be Shelton’s second in singles at a Grand Slam, having lost in the last four of the 2023 US Open to eventual champion Novak Djokovic.

He will face a tough task in either world number one Sinner or home hope De Minaur, who play later on Wednesday.