Scotland coach Gregor Townsend has suffered a double blow ahead of his first tour as national team boss, following the withdrawal of Richie Gray and Sam Hidalgo-Clyne.
Toulouse lock Gray was carrying a back complaint when he met up with the squad and will not be fit enough to take part in the three-Test trip.
Hidalgo-Clyne, a late call-up himself after Greig Laidlaw was summonsed by the British & Irish Lions, sustained a hamstring strain during training on Friday.
He will be replaced in the squad by uncapped Edinburgh scrum-half Sean Kennedy. Townsend has not called up a replacement for Gray.
"Richie has been unable to do much training since the Six Nations because of his back issues so it became quickly evident he wouldn't be able to play Test match rugby this summer," Townsend said.
"It was valuable having him in camp last week, spending time with the new coaching group, and we wish him well with his recovery and getting back to full fitness for next season.
"We're all disappointed for Sam who came into camp full of enthusiasm and worked really hard in our first three days together.
"While it's a blow for him to miss the tour, at least his injury isn't too serious and he can get back into preseason with Edinburgh at a later date.
"It's great that we have been able to call up a quality replacement in Sean Kennedy and we look forward to working with him over the next couple of weeks.
"His passing ability and conditioning level will fit in very well with the rugby we aspire to play."
Scotland kick off their tour against Italy in Singapore on June 10, before playing Australia in Sydney a week later and Fiji in Suva on June 24.