The Ospreys have agreed a deal to bring in London Irish prop Cai Griffiths on loan following injuries to Aaron Jarvis, Adam Jones and Joe Rees.
Griffiths previously spent nine years at the Ospreys, making 115 appearances, before moving to Irish in the summer.
However the 28-year-old, who has played six times for the Exiles, will now return - with the Ospreys also closing in on another tighthead prop.
Rugby operations manager Andy Lloyd told the region's official site: "To lose our three first choice tightheads to long-term injuries at the same time is unprecedented. Beyond that, although Adam is pencilled in to return early in the New Year, we expect to lose him to Wales again for the Six Nations in February and March.
"With Joe and Aaron out for the entire season that leaves us looking very bare in what is a crucial position.
"We are very close to completing a deal for an experienced tighthead to slot into our ERC squad on his arrival, and although Cai is ineligible for the Heineken Cup having played in the Amlin Cup this season he will have a big part to play over the remainder of our PRO12 campaign, particularly during the international period.
"He will provide experienced cover in a key position, one where we have been stripped of all our senior options, and importantly he is already familiar with the Ospreys way having been a loyal servant to the region for nine years previously."