ESSEX face a crunch Friends Provident tie at Lancashire today (Wednesday).
They appeared to be on the brink of qualification for the final stages but Monday’s defeat by Derbyshire stopped them in their tracks.
James Foster hit 71 as Essex scored 192 but, despite Danish Kaneria taking five for 32, Derbyshire got home with three wickets to spare.
The result ensures that Lancashire win Group D and are guaranteed a home tie on Saturday.
Essex currently have a better run-rate than Derbyshire and are two points ahead of their challengers going into each team's last round of matches.