Charles Piutau and Bundee Aki have been ruled out of the Barbarians' clash against England at Twickenham on Sunday.
Ulster's New Zealand international Piutau suffered an Achilles tendon strain ahead of the province's European Champions Cup play-off victory over the Ospreys two days ago.
Ireland and Connacht centre Aki, who was due to captain the Baa-Baas, is nursing an ankle injury.
"It was such a privilege to be named in the Barbarian squad this year but more so honoured to be named as captain," Aki tweeted.
"Unfortunately these things happen, and I'm absolutely gutted that I can't make it. Best of luck to the lads playing. Go well boys."
Aki's Connacht team-mates Denis Buckley, Ultan Dillane and Niyi Adeolokun have been named in the squad to face Eddie Jones’ side, who prevailed 28-14 to lift the Quilter Cup 12 months ago.
The Quilter Cup 🏆is coming soon...Sunday to be precise! 😎— Barbarian FC (@Barbarian_FC) May 22, 2018
Youth coaches say to tackle 'cheek to cheek' but sometimes curling up in a ball & riding the storm is the best method... 😂💥#rugby #rugbyunited 🏉 pic.twitter.com/Dv4wUby7o8