Hull City defender Alex Bruce and keeper Allan McGregor have been ruled out for between four and six months with "severe injuries".
Tigers boss Steve Bruce said McGregor had not recovered from the back injury that forced him out of the Championship play-offs.
The manager's son Alex has injured his Achilles and will also miss the start of the Premier League season.
"They're severe injuries and you don't want that at this particular time," said Bruce Sr.
"Surgery was always going to be the last resort with Allan because it's a horrible, complex operation."