Worcestershire 247 (Mitchell 118, Mennie 4-43, Clark 4-56) and 361 for 4 (Mitchell 163, Guptill 111) lead Lancashire 130 (Barnard 4-20) by 478 runs
If they are to avoid the fate that befell them in 2009, when they were relegated without winning a game, Worcestershire will not have a better chance than this. After a day that will carry several footnotes to the scorecard, they lead by 22 short of 500 with six wickets in hand.
It is a commanding position that would have been difficult to predict at a couple of points so far, Worcestershire having been 81 for 5 in their first innings and Lancashire 77 for 0 in the second.
But since Ed Barnard wreaked havoc in a 16-ball blitz that claimed four Lancashire wickets on the first evening the initiative has rested squarely with Worcestershire, all the more so as Joe Mennie has been withdrawn from the game because of concussion.
Martin Guptill, the New Zealand big hitter primarily hired to add Twenty20 firepower, marked his Championship debut for Worcestershire with a century, and Daryl Mitchell completed his second hundred of the match - the fourth time he has achieved that for his county.
Conditions that favoured the bowlers over the first four sessions of the match have clearly eased, to the extent that Lancashire, with their depth of batting experience and quality, will surely perform better once they bat again than they did in the first innings.
Therefore Worcestershire, already trailing by a long way at the bottom of the Division One table, will take no chances with their declaration and with two full days still remaining will bat on until their lead is truly unassailable, although the loss of three wickets in six balls shortly before the close suggests they might have had the best of this pitch.
Guptill is playing in two Championship matches - this one and next week's trip to Trent Bridge - before taking in the first eight matches of Worcestershire's Vitality T20 Blast campaign.
No cricket for two and a half months preceded his dismissal for two in the first innings, but he was clearly in better fettle this time and batted as if he was getting his eye in for short-form cricket, launching two sixes off Jordan Clark and another couple off Stephen Parry in reaching his hundred off 97 deliveries.
He was dropped on 70 by Shiv Chanderpaul at long leg off Parry, a miss that caused a frustrated Clark to hurl his cap into the turf at cover, and had to scramble home ahead of Haseeb Hameed's run-out attempt in taking the single that took him to three figures but until Tom Bailey hit him in front on 111 it was a pretty useful warm-up, one in which he had a few moments of good fortune on a still-tricky pitch but profited from a positive approach. It made him the first Worcestershire batsman to make a century on debut since Phil Jaques in 2006.
Guptill shared an opening stand of 215 with Mitchell, comfortably Worcestershire's biggest partnership of the season for any wicket, as the former captain turned the match into a personal triumph with his second century, again dominating the Lancashire bowling, which suffered for the loss of Joe Mennie, who bowled only four overs before his head injury forced him off the field.
By doubling up hundreds for the fourth time in a distinguished career, Mitchell can now claim to be on a par with Graeme Hick, the most prolific of all Worcestershire batsmen, even if his career-hundred count is a mere 32 for the county compared with Hick's 106. Mitchell's three previous 'doubles' were in Division Two matches, so this was a first.
Earlier, as Lancashire's first-evening collapse continued (all 10 wickets fell for 53 runs in 22.2 overs, five in 14.4 overs today), Barnard finished with 5 for 34, the remarkable fact of which was that all five victims failed to score a run: another collector's item on a remarkable day.