Title-chasing Lancashire are battling to stave off a second successive Championship defeat after conceding a first-innings lead of 197 to Nottinghamshire.
Ryan Sidebottom and Andrew Harris took three wickets each as the visitors were shot out for just 200 but hit back to reduce Nottinghamshire to 94 for 5.
The leaders Sussex were frustrated by Nick Knight's 123 at Edgbaston as Warwickshire made 329 for 7 on the first day.
Graham Onions took six wickets as Durham left Middlesex in deep trouble at Lord's. In reply to Durham's 409, Middlesex crashed to 176 all out and then slipped to 10 for 1 following on.
In the Second Division, Mike Powell's 299 for Glamorgan against Gloucestershire at Cheltenham helped the Welshmen declare on 647 for 7. Gloucestershire closed on 122 for one.
David Sales' 225 pushed Northamptonshire to 660 for 5 against Essex at Wantage Road. The visitors replied with 113 for 3.
Vikram Solanki's 140 gave Worcestershire a 33-run lead at Derbyshire.