Newcastle midfielder Joey Barton will undergo surgery on Monday after fracturing a metatarsal.
Barton joined Newcastle from Manchester City in June
The Magpies say Barton is likely to be sidelined for about six weeks after sustaining the injury in Saturday's 1-1 friendly draw with Carlisle.
A statement on the club website said: "He sustained a partial fracture of the fifth metatarsal in his left foot."
The 24-year-old England international only joined the Magpies in a £5.8m deal from Manchester City in June.
Barton made his debut for the Magpies against Hartlepool on Tuesday and manager Sam Allardyce made the £5.8m summer signing his captain at Carlisle.
Striker Michael Owen was omitted from the Newcastle line-up because of a minor thigh strain.
The 27-year-old England star picked up the injury in training.
Owen scored his first Newcastle goal in more than 19 months and Barton played well as Sam Allardyce's reign as manager began with a 3-1 win at Hartlepool.