Dropped on one, the England captain anchored Essex’s pursuit of 329 in 91 overs which looked like being successful when he shared a fifth wicket stand of 103 in 29 overs with Jesse Ryder.
But the ball after Ryder (35) brought up the century stand with a boundary, he was bowled off an inside edge trying to work leg-spinner Luke Wells into the off side.
Wells then had Ryan ten Doeschate brilliantly taken by the diving Matt Machan on the extra cover boundary and Essex called off the chase when James Foster became Ajmal Shahzad’s third victim of the innings, lbw trying to work the ball through the leg side.
When Sussex took the new ball they needed three wickets in ten overs but Cook was playing with such confidence by then and the captains shook hands on a draw on 266 for 7 after Graham Napier had kept Cook company for 40 tense minutes.
Sussex had missed their big chance in the fifth over. Steve Magoffin, who had pinned Nick Browne with his eighth ball, found the edge of Cook’s bat but Danny Briggs at slip put down a straightforward chance.
— County Championship (@CountyChamp) April 20, 2016
Cook endured a torrid opening to his innings. He survived a concerted appeal for lbw by Magoffin on two before putting down some roots as Essex, who lost Tom Westley on the stroke of lunch to Shahzad, added 14 runs in ten overs at the start of the afternoon session.
But with Cook settled and wickets in hand Essex were in a position to raise the tempo. Shahzad got some reverse swing to pin Dan Lawrence (22) but that was Sussex’s only success in the afternoon as Cook and Ryder began to build a substantial stand.
The 53 rd hundred of his first-class career may not have been his most fluent but Cook, who is due to play two more Championship matches for his county before he prepares for England’s series against Sri Lanka, played with increasing authority while Ryder signalled a change in tempo by hoisting Briggs down the ground for six.
When the last hour began Essex needed 95 off 16 overs but the loss of ten Doeschate and Foster fatally holed their ambitions.
Cook finished unbeaten on 127 from 246 balls with 13 fours but perhaps of more significance was that spent nearly six hours at the crease, giving him plenty of time to adjust to the new ECB-approved helmet he was wearing for only the second occasion.
Earlier, Jamie Porter completed his maiden Championship five-wicket haul by removing Shahzad for 23. The 22-year-old finished with 5 for 82, having shared the wickets with Napier (5 for 92) as Sussex were dismissed for 288.