ATP Paris, France
Ugo Humbert improves to 3-0 against Brandon Nakashima with Paris Masters win
Marcos Giron and Tallon Griekspoor also advanced Monday at the 1000-level event.
Griekspoor served more than twice as many aces as Ruud to earn a spot in the Stockholm semifinals.
The 6-1, 6-2 win was the 200th of Alcaraz's career.
The defending champion rallied from a set down for the second time in three matches to advance to the semifinals at the Libema Open.