Yorkshire spinner Azeem Rafiq has been ruled out for around six weeks because of a knee injury.
Rafiq played in the County Championship opener against Sussex and in last week's friendly with Lancashire.
Physio Scot McAllister told Yorkshire's website: "Raf has been complaining of a niggle to his knee, which has caused him some discomfort in recent weeks.
"We decided to send him for a scan on Friday, which revealed that he has a problem with his knee. We will now implement a full rehabilitation programme with a view to getting him back to full fitness within the next six weeks."
Rafiq, who captained Yorkshire t20 team last season, said: "I'm really disappointed to be missing out, with the season just getting underway.
"As a professional, all you want to do is play and to be sat on the sidelines for the next few weeks is going to be very frustrating. I'm going to work hard on my rehab with the medical team and hope to be back in action early June."
Rafiq's injury opens the door for Adil Rashid, who has been out of favour at Headingley but he may now get his chance against Durham for Wednesday's match.