Australia fast bowler Peter Siddle has been ruled out of Essex's Friends Life t20 campaign with a back injury.
Siddle had been due to join Essex as an overseas player for the competition's group stages in June and July.
But Siddle returned home early from Australia's West Indies tour and has been ordered to rest for a month before beginning a programme of rehabilitation.
Essex head coach Paul Grayson revealed the county planned to recruit an alternative overseas player.
He said: "We are very disappointed Peter can't make it to Essex following his injury.
"We understand that when we sign any overseas player that there is a risk of an injury or international duty so we now have to look at other options with a plan B for another overseas bowler."