Sir Tom Jones said he is "truly sorry" after rescheduling two forthcoming concerts due to "a bad case of the flu".
The 86-year-old singer from Pontypridd, Rhondda Cynon Taf, is currently on his Come Gather Round world tour.
He announced the decision to push back his Monday show in Los Angeles, and Tuesday's concert in San Diego, following doctor's advice.
In a post on Instagram, he wrote: "Following doctor's advice, I unfortunately have to reschedule tonight's show in Los Angeles and tomorrow's show in San Diego."
The San Diego concert will now take place at The Rady Shell, at Jacobs Park, on 3 November, while his Los Angeles show has been moved to 4 November.
On Instagram, he wrote: "I've had a great time these last few weeks, completing 20 shows and singing for wonderful audiences across the USA, but unexpectedly I've been hit with a bad case of the flu."
He added: "I'm truly sorry for any inconvenience caused. I look forward to seeing you all soon.
"All tickets for the original dates will remain valid. However, if customers are unable to attend the rescheduled dates, they are advised to contact their original point of purchase for a refund."
The post was shared just hours before he was expected to perform at the Greek Theatre, with the Los Angeles venue among those wishing Sir Tom well.
The It's Not Unusual and What's New Pussycat? singer recently made headlines after revealing ITV had "made the decision" to "fire" him from The Voice UK coaching panel.
Sir Tom, who has served as an on-off coach on the popular singing competition since its 2012 debut, shared the news on Instagram last month, amid speculation he had been "dropped" from its 2027 series.
The Delilah and She's A Lady singer has achieved three UK number one singles and four chart-topping albums during a music career spanning more than six decades.
His awards include one Grammy, two Brits and an Ivor Novello; Sir Tom also received a knighthood from the late Queen Elizabeth II in 2006 for his services to music.