DURHAM’S South African duo, Keaton Jennings and Michael Richardson, made half-centuries as the champions reached 174 for three from 64 overs at tea.
Jennings departed for 55 when he edged former Essex paceman Maurice Chambers to first slip, but Richardson remained unbeaten on 58 with Phil Mustard on 31.
Durham scored at two an over until the 39th, when Richardson pulled Andrew Hall for six and the runs began to flow.
Jennings cut and off-drove two successive balls from Azharullah to the boundary in the next over then his partner pulled Hall for two more fours.
A quick single took Jennings to 50 off 133 balls but after a fierce cut off Chambers took his boundary tally to eight he shaped to force the next one away off the back foot and got his fatal edge.
Richardson’s half-century came up off 114 balls with nine fours and a six, while Mustard took to his new role at No 5 in encouraging fashion, accumulating steadily.