The 26-year-old had been showing promising signs in his four-month battle to overcome a groin injury and was hoping to feature again this season.

But boss Paul Lambert confirmed the defender will go under the knife after suffering a setback in a midweek run-out with the reserves.

"Marc Tierney has had an operation on his groin injury and will be out until pre-season," said Lambert.

Fellow defender Daniel Ayala also made an injury comeback in the same game after shrugging off a knee injury that has kept him out for two months and like Tierney the former Liverpool man also broke down.

But Lambert was able to breathe a sigh of relief after the medical staff confirmed his setback was minor and he is still on track to feature this season.

"Ayala has seen specialist but hasn't needed surgery," he added.