Newcastle defender Steven Taylor is expected to be sidelined for the first three months of the new season.
The 24-year-old has undergone surgery after dislocating his left shoulder in a pre-season friendly at Carlisle on July 17.
The Magpies confirmed on their website: "After further assessment on the injury over the past week, the medical bulletin is that it will be a three-month period of rehabilitation."
The latest setback happened on the former England Under-21 captain's first appearance since suffering a knee injury in January.
His absence makes Tuesday's signing of Sol Campbell all the more timely. The veteran former England international was snapped up on a one-year deal after leaving Arsenal as a free agent.
Campbell will now compete with Fabricio Coloccini, Danny Simpson, Tamas Kadar and Mike Williamson for a place at the heart of Newcastle's defence in the early stages of the season.
In more positive news for the Magpies, young goalkeeper Tim Krul has signed a new four-year contract with the club. The Dutchman, 22, has impressed on his rare first-team appearances as understudy to Steve Harper and, before him, Shay Given, and has also had successful loan spells at Falkirk and Carlisle.
He told www.nufc.co.uk: "I am delighted to commit my future to Newcastle United, hopefully I can fulfil my dream by becoming the future number one goalkeeper as well as getting into the Dutch national team squad.
"I have been at the club for five years and it feels like home. I would like to thank Harps and Paul Barron for the guidance that they have shown me to date."
Manager Chris Hughton added: "We are delighted to have secured a four-year contract with Tim. He showed last season what an outstanding young goalkeeper he is and he can only get better."