Sussex 264 and 199 for 6 (Orr 57, Ibrahim 56*, Baker 3-31, Leach 3-44) lead Worcestershire 213 (Crocombe 3-44) by 250 runs
Dan Ibrahim gave another demonstration of his outstanding promise with an unbeaten half-century for Sussex on day three of the LV=Insurance County Championship encounter with Worcestershire at New Road.
Ibrahim celebrated his call-up into the England Under-19 squad for the forthcoming ODIs against the West Indies by making 56 not out to steer Sussex into a strong position.
He had become the youngest-ever player to score a half century in the County Championship against Yorkshire at Emirates Headingley in June at 16 years and 299 days. Today, he followed up his first-innings 48 and figures of 2 for 9 in nine overs in Worcestershire's first innings with another accomplished knock.
His efforts, coupled with a second half-century of the game from Ali Orr, enabled Sussex to reach 199 for 6 in their second innings - an overall lead of 250 - despite three wickets apiece for Joe Leach and Josh Baker.
Worcestershire resumed on 186 for 7 and the last three wickets fell for 27 runs in the space of 9.3 overs to earn Sussex a first-innings lead of 51.
Paceman Henry Crocombe dismissed Leach and Baker with successive deliveries - lbw and caught behind - while Fynn Hudson-Prentice held onto a return catch from Dillon Pennington.
The clatter of early-morning wickets continued during a devastating opening burst from Leach which reduced Sussex to 3 for 3. Sussex captain Tom Haines tried to work a delivery to leg and was caught off a leading edge by Tom Fell at first slip.
New batter Harrison Ward went leg-before to his first delivery from Leach and James Coles departed in the same manner.
The fourth wicket pair of Orr and Ollie Carter flourished after lunch and the former completed his second half-century of the game from 96 balls with seven fours and a six.
They added 84 before spinner Baker broke the stand with an excellent return catch - one-handed away to his right - to dismiss Carter for 20.
Baker then picked up the key wicket of Orr for 57 who checked his shot and presented the spinner with a far more straightforward caught and bowled at 98 for 5.
But a second substantial partnership of the innings was put together by Ibrahim and Hudson-Prentice. Their stand was worth 87 in 28 overs before Hudson-Prentice, on 46, gave Baker the charge and was stumped by Ben Cox.
Ibrahim had time to complete his fifty off 120 balls with six fours before bad light ended proceedings at 5.30pm.