Southgate is considering asking members of the Under-21s to make up the numbers in the build-up to the Euros if his squad is depleted by the absence of players from Chelsea, Manchester City, Manchester United or Arsenal.
The U-21s no longer have a summer tournament after crashing out of their Euros, but Southgate’s plan could put him at odds with clubs who would not want their young stars to continue training at the end of a gruelling season.
Southgate is expected to name his final squad on May 25, two days after the Premier League finishes but before the Europa League Final on May 26 and the Champions League Final on May 29.
Southgate wants all his players to have a week off after their final game of the season, but that would not be possible for Champions League finalists, with England due to host Austria in a warm-up game on June 2.
If Chelsea and City both make it to Istanbul, the earliest Southgate could call on Kyle Walker, John Stones, Raheem Sterling, Phil Foden, Reece James, Mason Mount and Ben Chilwell would be in England’s second warm-up match, against Romania on June 6.
Should Arsenal and United meet in Gdansk, Harry Maguire, Luke Shaw, Marcus Rashford, Mason Greenwood and Bukayo Saka may not play a full part against the Austrians.
Southgate is also considering decreasing the number of players on standby from five to two after Uefa indicated that nations could select an enlarged squad of 26 rather than 23 due to the pandemic.