Surrey need 249 for victory in their potential title decider against Nottinghamshire after persistent bad light interrupted play on day three at The Oval.
Rory Burns (41 not out) and Dom Sibley (18 unbeaten) took Surrey to 66 without loss at the close after Nottinghamshire, who had resumed on 219-8, extended their second-innings lead to 314 after being bowled out for 256.
Surrey's Matt Fisher followed up his five-wicket haul in the first innings with six for 73 to help leave the top-of-the-table clash hanging in the balance.
Somerset spinner Jack Leach took a season's best seven for 69 to help leave Hampshire bidding to avoid an innings defeat at Taunton.
The home side, who resumed on 381-7, declared on 454-8 - Kasey Aldridge, 149 not out overnight, was run out for 180 - and then skittled Hampshire out for 172 before the visitors, following on, reached 33-1 at the close.
In another match plagued by bad light at Hove, Sussex lead relegation-threatened Yorkshire by 38 runs with two first-innings wickets remaining after closing on 232-8 in reply to Yorkshire's 194 all out.
Resuming on 84-4, Sussex were indebted to wicketkeeper John Simpson's 66, while Ollie Robinson (unbeaten on seven) and Sean Hunt (five not out) will bid to extend the home side's lead.
Gareth Roderick (151) and Ethan Brookes (100) helped Worcestershire rack up 591-9 in their first innings, but their relegation was confirmed after they failed to secure a third batting point in the bottom-of-the-table clash with Durham at Chester-le-Street.
Roderick resumed on 95 and Worcestershire, 320 for five overnight, continued to pile on the runs thanks to Brookes, who moved from 50 to 100 in 45 deliveries, and Tom Taylor (66 not out).
Rain ensured no play on the third day in Warwickshire's match against Essex at Edgbaston, where the visitors hope to resume their first innings on 325-5 on Thursday.
In Division Two, play was abandoned on day three of already-promoted Leicestershire's home game against Kent without a ball being bowled due to a soaked outfield.
Kent will resume their first innings on 17 without loss on Thursday as they trail Leicestershire, who had declared on 459-7, by 442 runs.
At Derby, Glamorgan's promotion push was also stalled, with no play on the third day. Derbyshire are 17 without loss in their first innings after the visitors, who need 19 points to seal a top-two finish, were all out for 259.
Lancashire trail Middlesex by 106 runs with 10 wickets in hand at Old Trafford.
Lancashire closed on 105 without loss, with openers Luke Wells (60) and Keaton Jennings (36) both unbeaten after Middlesex were all out for 211. Home bowlers Tom Aspinwall and Tom Bailey took four wickets apiece.
In Bristol, play was curtailed before lunch as Gloucestershire reached 158-5 to trail by 48 runs, having resumed on 65-3 in reply to Northamptonshire's first-innings score of 206 all out.
