A half-century by Phil Mustard strengthened Durham's grip on their LV County Championship Division One match against Sussex at Chester-le-Street.
When the stroke-playing wicketkeeper went to the crease, 12 wickets had fallen on day two in 49 overs but only one went down in the remaining 45 as Durham closed on 212 for six, a lead of 345.
Mustard spent 137 balls making his unbeaten 57 and put on 93 in 36 overs for the sixth wicket with Paul Collingwood as they used their experience to prove that the pitch was no minefield.
The contest in the first half of the day was short of the quality expected between the second and third teams in the division, but both are depleted.
Sussex's batting looked very fragile after they resumed on 60 for three and lost Luke Wells early on before crashing to 112 all out.
Usman Arshad, playing his second first-class match, must have felt it was easy when he took three for 16 with his brisk medium pace and he later opened up with a straight six off Chris Nash on his way to 16 not out.
Nightwatchman James Anyon resisted well to make 19 before fending a return catch to Mitch Claydon and wicketkeeper Ben Brown remained unbeaten on 21.
Harry Finch, the 18-year-old debutant, scored 11 before Arshad had him lbw and he also had Will Beer and Steve Magoffin caught behind for ducks.
Claydon bowled last man Lewis Hatchett to finish with three for 25.
Durham led by 133 and, after his 96 in the first innings, Mark Stoneman again started fluently before a ball from Anyon which kept low had him lbw for 21.
The rest of the top five fell to edged catches, before Collingwood and Mustard set out to see off the dangerous Magoffin.
They succeeded but continued to grind out the runs as Chris Nash was in his tenth over of off spin and had conceded only 13 when Collingwood tried to work him to leg off the back foot and was lbw for 45.