Former world number one Andy Murray reached his first semi-final since the 2017 French Open with a battling three-set win over Romania's Marius Copil, in Antwerp, on Friday.

The 32-year-old British star, steadily rebuilding his career after major hip surgery earlier this year, defeated qualifier Copil 6-3, 6-7 (7/9), 6-4.

Murray, now ranked a lowly 243 in the world, had the chance to wrap up the quarter-final when he had a match point in the second set tiebreak.

He goes on to face either Argentine fifth seed Guido Pella or Ugo Humbert of France for a place in Sunday's final.

Italian teenager Jannik Sinner became the youngest ATP semi-finalist in five years when he defeated Frances Tiafoe of the United States 6-4, 3-6, 6-3.

Sinner, 18, is the youngest to make the last four on tour since 17-year-old Borna Coric at Basel in 2014.

"I think I played good today once more. It was not easy in the end. I was shaking a little bit," said Sinner, the world number 119.

The teenager fired 10 aces past the 53rd-ranked Tiafoe, saving four of five break points as he backed up his defeat of French top seed Gael Monfils in the second round.

Sinner, who was ranked 778 this time last year, can make the world top 100 next week.

However, he faces a daunting semi-final against three-time major winner Stan Wawrinka after the former world number three got past fellow 34-year-old Gilles Simon of France 6-3, 6-7 (6/8), 6-2 in his quarter-final.

Sinner, who lost to Wawrinka at the U.S. Open this year, will become the youngest ATP finalist since Kei Nishikori at Delray Beach in 2008 if he downs the experienced Swiss on Saturday.