Worcester prop Ceri Jones is set for months on the sidelines after undergoing shoulder surgery.
The 34-year-old former Wales international joined the Warriors from Harlequins last summer but picked up the injury in pre-season training.
Head coach Richard Hill told BBC Hereford and Worcester: "He was first injured on camp in Geneva but aggravated it against London Irish.
"He's had to undergo surgery. We all wish him well with his rehabilitation."
Hill added: "Ceri will be missed but Matt Mullan has been playing exceptionally well for us in the opening weeks of the season.
"His absence will also open the door for George Porter who has impressed us all since his arrival from Plymouth Albion in the summer and I'm sure will want to take this opportunity for more senior rugby."
Rookie hooker Ollie Hayes looks set for his first starting debut for Warriors at Bath in the LV= Cup on Saturday.
The 21-year-old joined them from Bristol in the summer, and came on as a replacement in the 20-19 win against Wasps in the LV= Cup on Saturday.
There will be full commentary on Bath against Worcester Warriors on Saturday 22 October (1415 BST) in 104FM and online at bbc.co.uk/herefordandworcester.