Watch highlights of day one
Relegated Northamptonshire's hopes of ending a wretched LV= County Championship Division One season on a winning note were dented by Sussex recovering well from an early stumble at Wantage Road.
At one point on the opening day, Sussex were tottering on seven for two, having lost Chris Nash and captain Ed Joyce, both sent back to the pavilion by Muhammad Azhar Ullah.
But the visitors recovered to reach stumps on 300 for seven, with the promise of more runs to come tomorrow.
Opener Luke Wells dropped anchor for a large part of the day to make 81, and his efforts were supplemented by Michael Yardy, with 56, and Ben Brown, who fell two short of a half-century.
Ashar Zaidi was unbeaten on 54 at the close, in an unbroken eighth-wicket partnership of 52 with Steve Magoffin.
Northamptonshire have yet to taste victory in the top flight this season, losing 12 of their previous 15 fixtures.
They started well, despite losing the toss on a bright morning in Northampton, as Azhar cleaned up Nash with his first ball before striking with the opening delivery of his second over when Joyce was trapped in front.
Wells, though, was proving harder to dislodge and he steadied the ship along with Craig Cachopa, who made 14 before he fell lbw to James Middlebrook on the day the veteran all-rounder was revealed to be leaving Northants after five seasons with the county.
WICKET! Yardy caught off the bowling of Olly Stone for 56. pic.twitter.com/X6aKfmmwzi
— Northants Cricket (@NorthantsCCC) September 23, 2014
Luke Wright was then caught behind shortly before lunch to give Azhar his third wicket of the morning and leave Sussex precariously placed on 76 for four.
Wells was still there, however, and he and Yardy managed to stage a recovery after lunch, with the latter settling to his task with two fours in three balls off Azhar.
Shortly after, Wells, who had scored the majority of his runs from boundaries, fittingly brought up a patient fifty off 121 balls with his 10th four.
The pair continued untroubled, with Yardy slightly more attacking to the obdurate Wells, and the former England all-rounder brought up his half-century off 82 balls with his seventh four.
The partnership ended four runs short of a century as Yardy fell to Olly Stone and, two balls later, Wells' 187-ball innings finished when he edged behind off Andrew Hall.
Any hopes that would trigger a collapse from Sussex, on 172 for six, were dealt a blow as Brown and Zaidi steadied the visitors.
Brown registered a breezy 48, which included six fours and a six, but fell two short of becoming the third half-centurion when he edged Stone to Hall in the slips.
Zaidi was more watchful but after putting on 76 with Brown, he added an unbroken 52 with Magoffin to leave Sussex well placed.
Zaidi brought up his half-century in the penultimate over of the day before cracking a four, with three balls remaining, which took his side to their third batting bonus point.