Ons Jabuer avenged her recent loss to Belinda Bencic with a win at the Madrid Open, while Coco Gauff is out after being beaten in straight sets in the round of 16 by Simona Halep on Monday.

Gauff joins other big names in exiting the WTA 1000 event, with Naomi Osaka, Garbine Muguruza, Danielle Collins, Paula Badosa and Maria Sakkari among those crashing out in the second round.

The number 14 seed did not put up much resistance against her Romanian opponent, with Halep winning 6-4 6-4 in just 77 minutes.

Gauff struggled on her own serve in particular, making six double faults and only winning 61.5 per cent of her first-serve points, compared to 83.8 from Halep on hers.

The former world number one and two-time Madrid champion will now face the only remaining top-eight seed in the tournament in the quarter-final, Jabeur, who defeated Bencic 6-2 3-6 6-2.

The Tunisian was out for revenge after losing to Bencic at the same stage last year, as well as in the Charleston Open final last month, and took it well as she sealed victory in just over two hours.

"I came here to take my revenge," Jabeur said after the win. "I wish I played like that in the final in Charleston, to be honest.

"Part of me is very proud of myself for coming today and getting the win. Belinda is such an amazing player and it's very tough to play against her. I'm very happy with the level I showed today, and hopefully this level will continue for the rest of the tournament."

Elsewhere, Victoria Azarenka is out after the number 15 seed was beaten 6-1 6-4 by Amanda Anisimova, who will now face Ekaterina Alexandrova in the last eight after she overcame Marie Bouzkova 6-7 (4-7) 6-0 7-5.