Worcestershire are on track to clinch their first Specsavers County Championship victory of the season despite the best efforts of Lancashire opener Keaton Jennings.
The England batsman’s 135 not out underpinned Lancashire’s 269-4 after they were set a mammoth victory target of 602.
However, with a further 333 required on the final day and only six wickets in hand, Lancashire face a battle to save the game.
Ben Cox was able to put Worcestershire further in the ascendancy, building on Thursday’s centuries from Daryl Mitchell and Martin Guptill with a quickfire 50 on a wicket offering little assistance for bowlers.
Danny Lamb had made history as he became the first concussion replacement in English first-class cricket, replacing Joe Mennie, who was struck on the head by a return drive from Guptill on Thursday.
Lamb, making his first-class bow, opened the bowling but found little joy, conceding 45 runs from his five overs as Worcestershire looked for quick runs.
Tom Bailey made early inroads by bowling Joe Clarke (10) and pinning stand-in captain Brett D’Oliveira in front but found Cox in inspired form, the wicketkeeper striking five fours and three sixes in his 58.
Ross Whiteley cleared the rope twice in his 23 as Worcestershire added 123 runs in 17 overs before declaring on 484-7 shortly before lunch.
Jennings and Alex Davies safely negotiated eight overs before the interval and then mixed solid defence with sound strokeplay as both registered a half-century within one over of each other.
It was only after D’Oliveira brought himself into the attack that the Lancashire duo looked uncomfortable.
He broke through when Davies (64) rocked back to play the cut shot and was LBW with the total on 126.
Haseeb Hameed accompanied Jennings in a stand of 58, but after making 20, he shouldered arms and became D’Oliveira’s second LBW victim.
Charlie Morris then had Shivnarine Chanderpaul (28) caught behind, having added 50 with Jennings.
Morris also enjoyed another success with Rob Jones (10) nicking through to Cox.
Jennings, though, had earlier gone to three figures, following on from last month’s hundreds against Somerset and Nottinghamshire – and he was still there at the close to give Lancashire hope of escaping defeat.