Monza (Italy): Dutch driver Nyck de Vries will make his Formula One race debut with Williams in Sunday's Italian Grand Prix as replacement for Alex Albon after the Thai driver was ruled out with appendicitis.
Williams said Albon, 26, felt unwell on Saturday morning and was undergoing treatment after seeking medical advice at a local hospital.
"Alex is in good spirits and the team wishes him a speedy recovery," the team added.
"Appendicitis, surgery and no racing isn’t what I was expecting this weekend!," Albon wrote on Twitter.
"Negatives: Missing out on what looks like a strong weekend for us. Pain. Positives: Weight reduction for Singapore. Cool scars."
De Vries, the 2019 Formula Two and 2021 Formula E champion, is a Mercedes reserve driver and has taken part in three Friday practice sessions this season with Mercedes-powered teams including Williams in Spain in May.
He was quicker in that session than Canadian regular Nicholas Latifi.
De Vries, 27, took part in Friday practice at Monza with Aston Martin -- in a rare example of a driver turning out for two different F1 constructors on the same weekend.
The combination of Latifi and de Vries on track together in race conditions has extra spice, with the Canadian's future uncertain after this season and de Vries on the list of potential replacements.
Another candidate is American F2 driver Logan Sargeant, who will take part in first Friday practice with Williams at next month's US Grand Prix in Austin, offering the scope for more comparisons.
Latifi is the only regular driver on the starting grid who has yet to score this season.
Former world champions Williams are last of the 10 teams in the standings.