Opening batsman Jason Roy has been ruled out of the rest of the T20 World Cup, the England and Wales Cricket Board announced on Monday.
Roy, 31, suffered a calf injury and collapsed to the ground while chasing a quick single in Saturday's 10-run loss to South Africa.
Roy has joined left-arm fast bowler Tymal Mills on the injured list in another blow to England, who lost to the West Indies in the final of the 2016 tournament.
"I'm gutted to be ruled out of the World Cup," said Roy in an England statement. "It is a bitter pill to swallow."
"I will be staying on to support the boys and hopefully we can go all the way and lift that trophy," added the Surrey star, a key member of the England side that won the 2019 50-over World Cup.
"We're all gutted for you @JasonRoy20," said a tweet on the England Cricket account.
"We will carry on playing in the positive spirit that you embody. If anyone can come back stronger, it's you."
There are a number of options for a replacement opening partner alongside Buttler including Jonny Bairstow, Liam Livingstone, Dawid Malan and Moeen Ali.
England arrived in the Gulf without the injured Ben Stokes, Jofra Archer and Sam Curran before Mills broke down with a thigh strain.
Morgan's side are bidding to become the first men's team to hold cricket's two major global limited-overs titles simultaneously.