Philippine wildcard Alexandra Eala has pulled off the biggest win of her young career with a stunning 6-2 7-5 upset of Polish world No.2 Iga Swiatek to extend her dream run at the Miami Open into the semi-finals.

The big-hitting 19-year-old left-hander showed no signs of intimidation playing against one of her idols and was instead a picture of poise as she dismantled Swiatek's serve early on in Wednesday's quarter-final clash to grab control of the match.

"I don't know what to say, I mean, complete just disbelief right now and I am on cloud nine," said Eala, who has lived the last six years in Mallorca, training at the Rafael Nadal Tennis Academy.

"It's forever in my heart."

Swiatek, who had been playing the match amid added security after she had been verbally abused by a spectator at the weekend, failed to hold serve throughout the first set while Eala was swinging freely as she unleashed winners from all over the court.

Five-times grand slam champion Swiatek hit a staggering 19 unforced errors in the opening set and then received some advice from her coach before briefly leaving the court.

In the second set, Eala managed to overturn a 4-2 deficit and then held her nerve while Swiatek tried to serve out the set at 5-4 before ultimately closing it out with her eighth break of the match.

For Australian Open girls' doubles winner Eala, the victory over Swiatek marked the third grand slam winner she had knocked out of the women's draw after earlier wins over Australian Open champion Madison Keys and 2017 French Open champion Jelena Ostapenko.

Up next for Eala will be American fourth seed Jessica Pegula, who beat 2021 US Open champion Emma Raducanu 6-4 6-7 (7-3) 6-2 in a two-hour, 25 minute battle.

Pegula's match ended at 11.23 pm (local time) and forced the postponement of the men's quarter-final between Novak Djokovic and Sebastian Korda until Thursday.

Asked after the match whether the security situation disrupted her preparation, Swiatek replied: "No, I wouldn't say so."

The WTA said player safety was their top priority.

"There are comprehensive security protocols in place to make sure that any incidents are handled promptly and effectively," the association said.

"The details of these are not something we discuss publicly, but we are steadfast in our commitment to maintaining a safe environment for players and everyone attending one of our events."

In a statement the Miami Open said it took the safety and security of all players and tournament attendees extremely seriously.

"We constantly evaluate any potential threats and take every measure to respond appropriately," the statement said.

"To ensure the effectiveness of these efforts, we do not disclose the details of our security operations."

At the Dubai Championships last month, Britain's Emma Raducanu said she could barely breathe and her eyes filled with tears when a stalker who had approached her earlier in the tournament was in the stands during her match.

Raducanu spoke to the chair umpire, and the man was ejected from the court and later detained by police.

With AP