The Ospreys medical team have confirmed that Hanno Dirksen will miss the start of the new season after suffering a setback as he recovers from surgery to repair a cartilage problem.
The South African-born winger impressed for the Ospreys throughout the 2011-2012 season, scoring eight tries.
Set to qualify to play for Wales on residency grounds in 2014, the 22-year old missed the majority of last season through injury.
The wing went under the knife last November and it had been anticipated that he would take part in pre-season but Head Physio, Chris Towers, says that will not now be the case.
"Hanno is behind where we originally predicted he would be at this stage after suffering complications that were beyond our control and which now appear to be remedied," said Towers.
"Due to those setbacks he is only just starting on the rehab process during the pre-season period. He is coping well but it will be a while yet until we will see him on the field training with the rest of the squad and we will update on expected return time when appropriate."