Having been skittled for 62 on Thursday they were reduced to 26 for three as they replied to Lancashire's 159 all out.
The second-placed home side resumed on 121 for eight and despite losing Stephen Parry and Simon Kerrigan cheaply, Tom Smith's 35 not out gave them a first-innings lead of 97.
Kyle Hogg, who claimed seven for 27 on Thursday, continued his purple patch with two for 17 before lunch with Glen Chapple bowling five maidens in eight overs as he claimed one for nine.
Moeen Ali progressed to an unbeaten double century as Worcestershire piled on the runs on the second day at home to Glamorgan.
He added 56 to his overnight total to be 211no at lunch as the team reached 438 for six as the visitors were lifted by taking three wickets, two going to Dean Cosker.
Leicestershire reached 98 for one at the interval after electing to bat at home to Essex.
Greg Smith went for 27 in the 21st over but Niall O'Brien (46no) and Ned Eckersley (17no) put on an unbeaten 40 for the second wicket.
- Sports & Recreation
- Simon Kerrigan