Sussex were made to follow-on as Worcestershire completed victory inside three days by an innings and 34 runs.
Despite a first innings century from Cheteshwar Pujara and a half century from loanee Grant Stewart, Sussex were unable to take the match into the final day.
Dillon Pennington, who dismissed Pujara twice today, with Charlie Morris, and Ed Barnard providing strong bowling support along with spinner, Josh Baker.
Sussex resumed on 169-5, still 322 runs in arrears, with their hopes pinned on Pujara who had scored an unbeaten 201 against Derbyshire in the previous match.
Pujara, unbeaten on 85 overnight, completed a fine century off 184 balls with 14 boundaries and he and Delray Rawlins negotiated the opening 50 minutes.
But the introduction of Pennington into the attack brought about a double breakthrough.
The former England Under-19 bowler has revealed his determination to perform on a more consistent basis this season and he soon shattered the stumps of Rawlins with a full-length delivery.
Pennington then picked up the prized wicket of Pujara (109) who edged a fine ball which nipped away and he was caught by Ed Pollock at first slip.
Tom Alsop, finally came into bat at number seven after a severely bruised finger had prevented him from batting in the top three.
But the home side continued to probe away on a cool and overcast day and Barnard found the edge of Grant Stewart’s bat with Pollock holding onto another chance.
Alsop, on 28, had been run out against Derbyshire last week and he suffered the same fate thanks to sharp work by Pennington.
He played a delivery from Barnard to wide mid-on, set off for a risky single and failed to beat Pennington’s direct hit at the non-striker’s end.
Morris wrapped up the innings when trapping Grant Burrows lbw on the stroke of lunch.
D’Oliveira’s decision to enforce the follow on soon brought dividends thanks to two wickets in two balls for Leach for the second time in the game.
Tom Haines nicked a fine delivery and keeper Ben Cox was alert to the situation and pouched a sharp catch in front of first slip.
The Leach-Cox combination then struck again to the next very delivery after Alsop pushed forward and found the outside edge.
Pennington then dismissed Pujara (12) for the second time in the day after knocking out his off stump.
Tom Clark was then tried to slog sweep Baker and inside-edged a catch to Cox and Mohammed Rizwan went lbw to Barnard.
A frustrating day for Sussex was summed up when Rawlins failed to beat Barnard’s throw to Baker at the non-striker’s end after a mix-up with Ali Orr.
Orr provided some stubborn resistance in making 33 off 138 balls but was undone by a Baker delivery which bounced on him and caught at short leg.
D’Oliveira held onto a good catch running back to long off to dismiss Henry Crocombe (8) to give Baker a third wicket.
Worcestershire’s Club Captain came into the attack for the first time and had Jamie Atkins caught at mid on.
Stewart struck Baker for four sixes in one over on his way to a 55-ball half century in some late defiance before Burrows went lbw to D’Oliveira to end proceedings.