John Isner progressed to the last four of the men's singles ©Getty Images

Defending champion John Isner progressed to the semi-finals of the Miami Open after battling past Spain's Roberto Bautista Agut at Hard Rock Stadium.

Little separated the two players in the opening stages of the quarter-final match, but Isner took the first set after winning seven of the eight points in the tie-break.

Bautista Agut aimed to stage another comeback following his three-set win over world number one Novak Djokovic of Serbia in the previous round of the Association of Tennis Professionals Masters 1000 competition.

He was denied by Isner as the American edged a second-set tie-break to emerge a 7-6, 7-6 winner.

Isner will face Canadian qualifier Félix Auger-Aliassime in the last four.

The 18-year-old Auger-Aliassime, the youngest player in the top 100 of the ATP rankings, continued his impressive tournament as he overcame Croatia’s Borna Ćorić 7-6, 6-2.

Simona Halep is one win away from reclaiming the world number one ranking ©Getty Images
Simona Halep is one win away from reclaiming the world number one ranking ©Getty Images

World number two Simona Halep advanced to the semi-finals of the Women’s Tennis Association event.

The Romanian earned a 6-4, 7-5 win over China’s Qiang Wang.

She will face Karolina Pliskova in the last four.

Pliskova was a 6-3, 6-4 winner in an all-Czech quarter-final against Marketa Vondrousova.

Should Halep win the semi-final, she would reclaim the world number one ranking from Japan’s Naomi Osaka.