Ipswich have been forced to register 40-year-old coach Andy Rhodes to solve a goalkeeping crisis. He is likely be on the bench at Watford after 17-year-old Shane Supple suffered a suspected broken toe in action for the reserves on Wednesday.
Lewis Price will continue to deputise for first choice Kelvin Davis, who is still ruled out by a back problem.
Rhodes, who took up his post in the summer, has not played a senior game in almost six years.
Royle said: "Going without a keeper on the bench is one possibility, but we have also decided to register Andy.
"He played in a charity game for Oldham last year and knows what to do and where to be, but I wouldn't like to see him on the pitch at Watford for any length of time."