Ospreys prop Aaron Jarvis has been ruled out for the rest of the season due to a knee injury sustained in Wales' loss to New Zealand in Cardiff last week.
Jarvis joins two other Ospreys tightheads on the injury list, with Adam Jones also sidelined with a knee injury and Joe Rees ruled out for a "lengthy period of time" after undergoing neck surgery this week.
Ospreys head physio, Chris Towers, revealed that Jarvis will have to undergo an operation.
"Aaron suffered a significant ligament injury to his right knee in the Wales v New Zealand game on Saturday," he said.
"He is going to require surgery and will miss the remainder of the 2012/13 season.
"We are currently in discussions with specialists to establish the best surgical option and timing of the surgery to ensure the best outcome"
Andrew Hore, Chief Operations Officer at the Ospreys said Jarvis' injury was a huge setback at an important stage of the season.
"We have now lost three senior tightheads in the space of just a month, which is particularly bad news for us, coming at a time when our resources have already been badly hit through injury and just before our biggest games of the season so far, the back-to-back Heineken Cup matches against Toulouse," he said.
"The current season structure sees games in the top European competition go straight into a month of test rugby, and then back into Europe and the Welsh derbies, for a crucial month long period in December and January.
"Looking at the players we have lost through injury in recent weeks it's clear that the structure isn't working, for the national body nor the regional partners, and it needs to be looked at globally.
"If ever there was a time which perfectly highlights the need for a structured, global season which protects our biggest assets, the players, and increases the value of domestic rugby by ensuring showpiece matches are played with the strongest squad available then this is it."