St Johnstone captain Dave Mackay has been ruled out for the rest of the season.
The veteran defender will undergo his second hip operation in less than a year, and is expected to be sidelined for at least four months.
Perth boss Tommy Wright has moved quickly to bring in defensive cover – former Alloa and Kilmarnock right-back Michael Doyle.
Wright said: “Dave’s been able to manage the problem since returning to action but he has been in a lot of discomfort this week and so we sent him for further consultation and the outcome is that he needs another operation.
“He’s looking an absence of four to five months so unfortunately his season is over.
“I’m very disappointed for him because he put a lot of work into his recovery back in the summer and autumn.”
Doyle goes straight into the squad for Saturday’s visit of Aberdeen.
Wright added: “I know Michael well. He was about to sign for Cork City but wants full-time football in Scotland and this opportunity has come up at the right time for him. He’s a good athlete and experienced and will give us good cover at a critical stage in the season.”
* See Friday’s Courier for full interview with Wright.
