Somerset seized top spot in the County Championship on a dramatic penultimate day of the season - but face an anxious wait to see if they will stay there.
Chris Rogers' side will claim their maiden title if the match between Middlesex and Yorkshire at Lord's ends in a draw on Friday.
Any other result will see the victors at headquarters crowned champions.
Somerset, third heading into the final round of fixtures, kept their hopes alive as they completed an emphatic 325-run win over Nottinghamshire at Taunton to knock Middlesex off the summit.
Rogers - who announced his retirement immediately after the game - hit his second century of the match (100 not out) as the hosts set Notts an unlikely target of 541. There were also half-centuries for Ryan Davies and Peter Trego.
Billy Root, brother of England's Joe, offered some resistance for Notts with an unbeaten 66 but Jack Leach (4-69) and Roelof van der Merwe (3-59) hastened their demise as they were shot out for 215.
That result meant Middlesex's clash with Yorkshire became a winner-takes-all encounter and the situation was delicately poised at the end of a see-saw third day.
Middlesex closed on 2-81 in their second innings, trailing by 39, having regained some composure after Yorkshire - and specifically Tim Bresnan - turned the game on its head.
All of the hosts' early control completely dissipated as Bresnan, who came to the crease at 3-32 on Wednesday, guided the champions to a first-innings lead of 120 with a superb unbeaten 142.
His final-wicket partnership with Ryan Sidebottom (23) was worth 56 and ensured Yorkshire secured a critical fourth batting bonus point and went on to reach 390.
Middlesex slipped to 2-2 as they lost Sam Robson and Nick Compton early in their second innings but Nick Gubbins (39no) and Dawid Malan (37no) steadied the ship for the home side.
The battle to avoid relegation was looking equally likely to go to the wire with Hampshire battling hard and Lancashire, especially, looking over their shoulders.
Hampshire need to win to stay up and they gave themselves a chance as they built up a 226-run lead over Durham with three second-innings wickets remaining at the Ageas Bowl.
Rain prevented play early in the day but they eventually finished off Durham's first innings for 361 to lead by 50 at the mid-point. Durham's Michael Richardson was left stranded on 99 not out while Brad Wheal and Liam Dawson took four wickets apiece.
Hampshire then closed on 176 for seven after Ryan Pringle took 5-64, but Lewis McManus (41no) offered hope of setting a stiff target.
Victory for Hampshire would relegate the losers of Warwickshire and Lancashire at Edgbaston and the Red Rose were in trouble.
Lancashire were 28 for three having been set a target of 347 after Warwickshire declared on 279 for seven. A draw would see Lancashire survive.