Jones suffers calf strain
Ospreys forward Ryan Jones' injury-hit start to the season has suffered another setback with a calf strain sustained in training.
The former Wales captain has made just one appearance this term, facing Treviso in the RaboDirect Pro12 on the opening night of the season and lasting just 48 minutes before injury struck.
Jones was hoping to make his comeback against Ulster on Friday, but will not now be fit for that clash.
"The problem Ryan has is that he trained last week and pulled up with a calf strain, to go on top of what he's already been dealing with," Ospreys' forwards coach Chris Gibbes told the South Wales Evening Post.
"How serious is this latest bump? It's enough for him not to be able to play. We are just going to need to assess where he's at as we go through this week.
"We feel for him. He's a huge part of our team and to have a guy like that involved in the squad is massive.
"It's unfortunate for Ryan, but others guys will have their opportunities."