Returning to action for the first time since Saturday’s One-Day Cup final triumph, already relegated Worcestershire were brought back down to earth with a bump, as a searing Robinson spell saw the England seamer take four wickets in the first hour.
Youngster Rehaan Edavalath was caught behind with the third ball of the match, before Pears skipper Jake Libby saw his off-stump sent flying after facing just one ball as the Pears fell to 1-2.
Teenager Lategan provided a classy counter-attacking cameo for the hosts, easing the ball through the vacant offside whenever the opportunity arose.
But Robinson continued his unrelenting start to the morning, claiming two further scalps, including that of first-class debutant Isaac Mohammed who was pinned lbw, with a sobering opening hour rounded off with the dismissal of Rob Jones who suffered the same fate, leaving his side in a heap at 36-4.
Lategan continued his riposte but Worcestershire woes deepened with Roderick caught behind off the bowling of Unadkat, before Robinson collected his fifth wicket of a superb spell by removing the key man, Lategan, for his resolute 41.
Robinson almost secured his sixth wicket on a morning session dominated by the bowlers, but the umpires were not convinced Simpson had held on to a rebound catch behind, as lunch was taken with Worcestershire 91-6.
Unadkat picked up where he left off after the resumption as Ethan Brookes became his second victim with a regulation catch provided to Coles at slip.
He took his season’s tally of wickets to 13, after removing Tom Taylor caught behind for nine and trapping Ben Allison in front without scoring as the Pears’ landslide continued.
Robinson completed his six-fer with the wicket of Waite, who was the last man out.
The Pears hit back in resilient fashion as Allison led the way in an inspired early spell, taking three wickets to help reduce Sussex to 67-4.
The seamer first trapped Hughes (24) lbw, before taking a stunning one-handed caught and bowled to remove Carter and bowling Alsop for just one, while Taylor took his 51st Championship wicket of the season to drag the hosts back into the contest.
Simpson and Coles led the Sussex revival however, dominating an afternoon session that saw the fifth wicket pair add 90 runs before tea, with Coles reaching a fluent fifty in the process.
Both batters moved past 1,000 first-class for the season during the evening session, with Coles reaching his century from 105 balls, before he was bowled by Ben Gibbon as Simpson helped close a dominant day for the visitors on 228-5, leading by 105 runs as bad light stopped play.
Match report supplied by ECB Reporters’ Network, supported by Rothesay