Relegation looms ever larger for Lancashire after Worcestershire restricted them to a solitary batting point in their crucial clash at New Road.
The hosts, still with a game in hand, closed the gap at the bottom of the table after dismissing last year's champions for 216 in a draw that ended as a scrap for bonus points.
Gareth Andrew led the way with a season's-best return of 4-42 and Moeen Ali, who captured 12 wickets in his side's win at Old Trafford in July, polished off the lower order with 3-46.
Paul Horton was first to go in the ninth over of the final morning and after that, each time a partnership began to develop the visitors would lose a cluster of wickets as Worcestershire attacked non-stop.
Ashwell Prince, Andrea Agathangelou and Steven Croft were caught behind in the space of five deliveries from Richardson and Andrew.
Young all-rounder Joe Leach claimed his first championship wicket with the dismissal of top scorer Gareth Cross (39) and Moeen mopped up. Worcestershire were on 33-0 in their second innings when a draw was agreed at 4.50pm.
Lancashire ended day three on 10 without loss after relegation rivals Worcestershire declared on 251-7 in a rain-affected match at New Road.
The match was at a standstill for more than five hours before Gareth Andrew and Ben Scott came out to add 27 runs to the Pears' overnight score.
Only eight overs were squeezed in before lunch but that was enough to dash Worcestershire batsman Neil Pinner's hopes of making a maiden century some 15 months after being dismissed for a duck in his only previous LV= County Championship innings.
Scott (14 not out) twice drove Kyle Hogg for four and when Andrew (12 not out) clipped the same bowler backward of square to register a second bonus point, Daryl Mitchell called his side in.
All-rounder Luke Procter, promoted to the top of the order after Stephen Moore was left out, nudged the only boundary off Chris Russell at the start of Lancashire's reply.
Where the game goes from here depends on whether the captains are prepared to strike a deal. Otherwise the last day is set to be a battle for bonus points.
Rookies Neil Pinner and Joe Leach defied relegation rivals Lancashire as Worcestershire closed day two on 219-6 in their crucial LV= County Championship first division clash.
When the game got underway after a first-day wash-out, Glen Chapple and Kyle Hogg led the fight to keep Lancashire in the top flight.
The troubled hosts were on the back foot in Chapple's second over when skipper Daryl Mitchell popped up a bat-pad catch to Simon Kerrigan.
When Hogg got one to swing into James Cameron's pads, a familiar story was in the making as Worcestershire lurched to 17-2 by the 12th over.
Left handers Matt Pardoe (37) and Moeen Ali (35), eked out a stand of 45 in 20 overs. Moeen curbed his stroke-playing instincts when taking 22 balls to get off the mark.
Batting was never easy but just as the third pair seemed to be gaining the upper hand, Chapple landed a double blow with the help of two catches by Gareth Cross in the space of eight balls.
Cross quickly adjusted his position to hold an inside edge from Vikram Solanki while Moeen carried on the struggle for 11 more overs until he drove across a leg-stump delivery from Hogg.
The opening day of the County Championship match between Division One relegation rivals Worcestershire and Lancashire was washed out after a prolonged downpour at New Road.
The rain set in as the captains, Daryl Mitchell and Glen Chapple, were preparing to toss the coin and in a couple of hours pools of water formed close to the covers on the pavilion side of the ground.
Umpires Trevor Jesty and David Millns called for an early lunch but conditions only worsened until they made the inevitable decision to abandon play for the day at 2.25pm.
Worcestershire are without top batsman Phil Hughes after his call-up to the Australia A side playing England Lions at Edgbaston.
With leg-spinner Brett D'Oliveira rested after last week's seven-wicket defeat by Warwickshire, director of cricket Steve Rhodes brought batsmen James Cameron and Neil Pinner into the squad.
Lancashire left out Stephen Moore for the meeting with his former county following his run of 20 championship innings without a half-century this season. All-rounder Luke Procter returns after injury.