Eugenie Bouchard beat Maria Sharapova for the first time in her career soon after calling the former world number one a "cheater" to set up a meeting with Angelique Kerber, while Anastasija Sevastova shocked Karolina Pliskova at the Madrid Open.
Bouchard recently stated that she believes Sharapova's tennis career should have been over when she failed a drugs test at the Australian Open last year.
All eyes were on the Spanish capital when the two met less than a fortnight after that candid interview with the 2014 Wimbledon runner-up, who raised her game to defeat the former world number one 7-5 2-6 6-4 in a second-round thriller.
Top seed Kerber earlier made hard work of seeing off Katerina Siniakova 6-2 1-6 7-5 to ensure she will return to the top of the rankings in the absence of the pregnant Serena Williams, but second seed Pliskova went down 6-3 6-3 to the 22-ranked Latvian Sevastova.
FIRED-UP BOUCHARD DELIVERS ANOTHER SHARAPOVA BARRAGE
Bouchard let her feelings be known in no uncertain terms when asked about Sharapova's return to the circuit last month.
And the Canadian made another huge on-court statement on Monday, showing great spirit and plenty of class to topple the five-time grand slam champion.
Sharapova had won their previous four meetings, but Bouchard looked to be back to something like her best as she showed flashed of brilliance to win a gripping showdown.
The match swung one way and another before Bouchard fittingly clinched it with a sublime forehand winner. The pair shook hands at the net, but the tension was still unsurprisingly evident.
KERBER OVERCOMES SINIAKOVA CHALLENGE
Kerber was in danger of being on the end of a shock exit at the hands of 20-year-old Siniakova, but won four games in a row to advance.
Bouchard will be Kerber's next opponent after the two-time major champion fought back from 5-3 down in the deciding set to make the last 16.
The German will replace Williams as world number one next week after a hard-fought success.
Kerber said: "I think she played one of the best matches in this year. I was trying at the end coming back. I know that I can come back and win matches like that when I'm down, so that was actually what was going on in my mind in the third set."
SEVASTOVA POWERS PAST PLISKOVA
Sevastova beat Johanna Konta in Stuttgart last week and had too much for world number three Pliskova in Madrid.
The Latvian won seven consecutive games after finding herself 3-2 down in the opening set and Pliskova was unable to come up with a solitary break as she made an early exit.
Caroline Wozniacki was also beaten in round two, losing to Carla Suarez Navarro in the last match of the day. Svetlana Kuznetsova, Kristina Mladenovic and Lara Arruabarrena were all winners on day three of the tournament.