Top seed Elise Mertens saw off Sara Errani to reach the Grand Prix De SAR La Princesse Lalla Meryem semi-finals.
The 22-year-old Belgian prevailed 6-3 6-1 for her second win over the Italian in 2018, booking a last-four showdown with either Katarina Zavatska or Hsieh Su-wei in Rabat.
"Even though the score was three and one (games), I think it was a very tough match," said Mertens on court after victory, according to the WTA website.
"She's a great player, got a lot of balls back, and of course she has a lot of experience.
"All credit to her, she's still on the tour, she's still as fit as ever.
"So I'm really happy that I won, I played a good level and knew what to do."
Elsewhere in Rabat, Ajla Tomljanovic battled past Jana Fett 3-6 6-3 6-3 and Paula Badosa Gilbert retired injured, handing victory to Aleksandra Krunic, who was leading 6-2 1-0.
Mihaela Buzarnescu eased past Kristyna Pliskova to reach the semi-finals at the Prague Open.
The seventh seed will face Camila Giorgi in the last four, with the Italian seeing off Sam Stosur 6-2 6-3.
"I'm really happy about this result because it's been quite a few tough months," Romanian Buzarnescu told the WTA website.
"I'm happy I was able to win three matches in a row."
Elsewhere in Prague, second seed Petra Kvitova secured a routine 6-3 6-3 win over Katerina Siniakova and Zhang Shuai moved beat Jasmine Paolini 6-4 6-3.