Essex captain James Foster will have to wait for up to two days before finding out how long he will be sidelined by an ankle injury.
The 31-year-old suffered a lateral sprain in training on Tuesday and will definitely miss Wednesday's Clydesdale Bank 40 clash against Glamorgan.
"It is hard to say how long this will keep me out for until we have a look at it in a couple of days," he said.
The wicketkeeper-batsman had returned from a two-match ban 10 days ago.
His side are unbeaten in the Clydesdale Bank 40 so far this season, having won four of their six matches, with two ending up as no results.
Foster has scored 143 runs in his two innings in the competition.