Back-row forward Ieuan Jones will remain at the Ospreys into the new year after extending his loan from Blues.
The 21-year-old from Aberbargoed joined Ospreys at the end of October on an emergency one-month loan as cover for injuries and international call-ups.
He has made three appearances for the region to date.
"We are grateful to the Blues for allowing him to stay with us until after the Six Nations," said Ospreys rugby manager Andrew Millward.
"Ieuan has done really well since coming to the Ospreys as emergency cover.
"It's a crucial period for the region so to have someone like Ieuan available, with his positive attitude on and off the field, is a real bonus for us."
Ospreys back-row players Dan Baker and Joe Bearman are both sidelined with long-term injuries.
Jones is not registered for the European Rugby Champions Cup, but will provide cover for Pro 12 games.