Emma Raducanu's encouraging Miami Open run came to an end in a narrow quarter-final defeat by world number four Jessica Pegula.

Despite needing medical treatment, the 22-year-old Briton levelled the match before American Pegula clinically regained control to win 6-4 6-7 (3-7) 6-2.

In the second set Raducanu played some of her best tennis since becoming a teenage Grand Slam champion at the 2021 US Open.

The world number 60 held a 5-2 lead and had four set points in the eighth game, before calling to see the doctor.

She had her blood pressure taken and was given ice towels to cool down before resuming.

The way in which Raducanu showed fortitude and fight to win the second set was impressive.

But she could not see the job through as Pegula demonstrated why she is one of the most consistent competitors on the WTA Tour.

"It was tough," said US Open runner-up Pegula. "I just wanted to come out in the third set really strong, really quick, and jump on her."

The 31-year-old will play 19-year-old Alexandra Eala from the Philippines in the semi-finals on Friday.

Eala continued her remarkable run by causing a seismic shock against five-time major champion Iga Swiatek earlier on Wednesday.

Questions have frequently been asked about Raducanu's physical and mental resilience since her breakout victory in New York more than three years ago.

Raducanu found the transition to being full-time on the tour difficult, with a series of injuries hampering her progress and the weight of scrutiny proving heavy.

Issues have continued to arise.

During a testing start to this season, Raducanu has dealt with a back injury, been targeted by a stalker and had her trusted coach Nick Cavaday leave.

In Miami she gave a reminder that she has the ability - and guts - to compete with the world's best.

Although she lost to Pegula, there were eye-catching victories over top-20 opponents Emma Navarro and Amanda Anisimova on her way to reaching the quarter-finals at a WTA 1000 event for the first time.

Raducanu will also take great satisfaction from knowing she will return to the top 50 of the WTA rankings next week.

Stringing together four victories in a row - for the first time at a tournament since her US Open triumph - was another sign of her progress.

Now Raducanu will look to build on her improved level and deliver the greater consistency she is striving to find when she moves onto the European clay-court swing next month.

Raducanu found form in Miami with a more relaxed approach, which allowed her to play with greater freedom.

Raducanu decided to abandon a trial partnership with Slovak coach Vladimir Platenik coming into the tournament, asking for guidance from some familiar faces instead.

Mark Petchey, a well-known figure in British tennis who coached Raducanu in her teenage years, joined her long-time confidante Jane O'Donoghue and fitness coach Yutaka Nakamura.

Raducanu said the set-up allowed her to be "authentic" and "express" herself on court - and it showed against Pegula with her clean ball-striking and sharp movement.

Pegula's solid groundstrokes offered few errors and a single break was enough for Raducanu to lose the opening set.

Raducanu was heartened by the quality of her play, though.

Adopting a more aggressive approach in the second set paid dividends as she dominated Pegula, quickly getting her reward with an early break as momentum shifted.

When Raducanu could not level with the double break, amid complaining of dizziness, it felt like she was there for the taking when she returned from the medical timeout.

But she showed remarkable mental toughness to hold serve for 6-5, managing to step up her level again in a superb tie-break, before Pegula outlasted her in the decider.