World number one Iga Swiatek beat Romania's Sorana Cirstea 6-1 6-1 to reach the last 16 of the Madrid Masters.
The Polish top seed, a three-time winner of the French Open, needed only one hour and 18 minutes to win a one-sided third-round match on her favoured surface.
Swiatek, runner-up to Aryna Sabalenka in Madrid last year, will face Belarusian Victoria Azarenka or Spain's Sara Sorribes Tormo next.
"Victoria is a really experienced player who plays well on every surface," said Swiatek.
"Sara is a Spaniard, will have the home crowd behind her, and is really solid.