Keshav Maharaj, the South Africa spinner, has been ruled out of a planned stint with Middlesex after rupturing his Achilles tendon during the Johannesburg Test against West Indies.
Maharaj is expected to be out for six months after suffering the injury while celebrating a dismissal on day four of the Test, putting his participation at the World Cup later this year at risk.
He had been due to join up with Middlesex in April for a spell of eight County Championship fixtures and the Vitality Blast.
Middlesex's director of cricket, Alan Coleman, said: "We are naturally extremely disappointed that Keshav will not be joining Middlesex this year after sustaining this freak injury and we are saddened to hear that he will face a significant absence from playing. It goes without saying that everyone at the club wishes him a speedy recovery.
"For us to lose Kesh so close to the start of the new season is a blow, however he wasn't scheduled to begin playing for us until late April, which buys us a little time to put Plan B into action. We will of course keep everyone updated on the situation regarding a replacement overseas player for the coming season."