ACAPULCO, Mexico - World No.183 Stefanie Voegele played well above her ranking to stun 2016 Acapulco champ and current top seed Sloane Stephens in the quarterfinals at the Abierto Mexicano TELCEL presentado por HSBC.

Aggressive from start to finish against a lethargic-looking Stephens, Voegele’s 6-4, 5-7, 6-2 victory  over the reigning US Open champion marks a full-circle moment for the 27-year-old Swiss player. Incredibly, it’s Voegele’s first Top 20 victory in almost five years - since her defeat of then-No.13-ranked Stephens in Tokyo in 2013.

Read more: Stephens staves off Rus test in Acapulco second round

And like Stephens, Voegele came into Acapulco seeking her first WTA match win of the year. She found her groove in the seaside Mexican resort town, posting back-to-back wins over Tatjana Maria and Maria Sakkari in straight sets before taking on familiar foe Stephens in the quarterfinals.

Voegele owns a 3-1 lead over the American in their head-to-head record, but they hadn’t faced off since that match in Tokyo in 2013, when the Swiss was at her career-high ranking of No.42.

For her part, Stephens had a much more dramatic road to the quarterfinals than her opponent; after cruising in the first round to Pauline Parmentier, she had to save match points in her next match against Arantxa Rus to come back from a set down and win 5-7, 7-6(6), 6-0.

Against Voegele, Stephens started off sluggish, errors coming thick off her backhand and her timing just a beat too slow. The Swiss took full advantage, taking the ball early and trading breaks twice with Stephens before closing out the first set with a decisive break in the final game.

In the second, it was Stephens who took the lead - she took the pace off of her first serves and raised her level of aggression to break early, building up a 3-1 lead. Voegele dug her way out of trouble again, breaking back at 3-3 and keeping the pressure on Stephens. But Stephens rose to the occasion, reeling off the last three games of the set to level the match at one set apiece.

But Stephens couldn’t keep up the intensity in the final set. She put in a monumental effort to get the break back after Voegele once again got off to an early lead, but the Swiss recovered strongly to break twice more to close out the match, dropping just two points in four games.

Voegele will face either No.4 seed Zhang Shuai or qualifier Rebecca Peterson in the Acapulco semifinals; a victory would earn her a spot in her career-first WTA-level final.

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