The 32-year-old from Pakistan, who took ten wickets against the same opponents in 2014, helped dismiss Sussex for 178 despite 75 from opener Chris Nash. Northants then reached 43 for 1 in reply when play ended at 7.57pm with six overs of the day’s allocation not bowled because of bad light.
Azharullah benefitted from bowling a full length and letting the overcast, humid conditions do the rest, although he was also helped by indifferent shot selection by some of Sussex’s batsmen.
Nash and Ed Joyce put on 42 in ten overs without alarm but Sussex’s troubles began when Azharullah bowled Joyce (10) off his pads and he then struck with successive balls in his next over. Luke Wells (5) drove loosely to become the first of five victims for wicketkeeper David Murphy and Harry Finch was lbw to a ball which swung back in.
Nash reached 50 from just 53 balls and the ease with which he stroked the ball through his strong off-side areas was in vivid contrast to the struggles of his team-mates.
Luke Wright, leading Sussex in the Championship for the first time, looked understandably rusty and Azharullah picked him up for 14 when he switched to the Castle End.
Matt Machan was dropped at slip by skipper Alex Wakely on five and helped put on 46 either side of tea before four more wickets fell in 33 deliveries.
Azharullah collected the first two with Machan (30) caught behind driving before Ben Brown (3) became his sixth victim, courtesy of a fine low diving catch in front of slip by Murphy.
Ollie Robinson was then foxed by Ben Sanderson’s slower ball, which he drove to extra cover where debutant Shaun Terry took the catch on the day he became the 500th player to play first-class cricket for Northamptonshire.
Nash, who had made 75 from 119 balls with ten fours, was eighth out when he was surprised by extra bounce from Richard Gleeson and edged behind.
The persevering Ben Sanderson removed Steve Magoffin (5). Ajmal Shahzad and Stuart Whittingham added 23 for the last wicket before Shahzad was caught at deep mid-wicket off off-spinner Richard Keogh.
Northants began their reply at 6.50pm and opener Rob Newton lost his off stump to Ollie Robinson for a 24-ball duck but Ben Duckett and Wakely saw them safely through to the belated close.
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