Yorkshire 24 for 0 trail Worcestershire 389 (D'Oliveira 103, Kashif Ali 93, Allison 75) by 365 runs
Brett D'Oliveira, Worcestershire's captain, said that he would take pride in securing a special place in both the club's history, and his own family history within it, after his century led the way in their promotion back to Division One of the LV= Insurance County Championship.
The club secured second place in Division One, behind champions Durham, by reaching 300 for a second batting bonus point during the early stages of a weather-interrupted second day against Yorkshire at Headingley on Wednesday.
Worcestershire started this fixture needing a maximum of two points to seal top-flight cricket for 2024 and extinguish Leicestershire's slim chance of overhauling them. They were 280 for 5 overnight.
While captain D'Oliveira was their star man by moving from 90 overnight to complete a superb 103, he fell lbw to Matt Milnes to leave the score 299 for 6 and left it to Josh Baker to hit the landmark runs before they were bowled out for 389.
The Pears were stuck on 299 for 10 balls before Baker pushed Milnes through the covers for two at 10.55am - 25 minutes into day two - sparking celebrations on the players' balcony from his team-mates and coaches.
"It's an amazing feeling," D'Oliveira said afterwards. "It's something that we've been working really hard towards. It's relieving to get over the line.
"It's not just the eleven lads who take the field. There's a lot of hard work which goes on behind the scenes. You go right back to the ground staff and the amazing work they put in and everyone else at the club. It's really pleasing to reward the club with promotion.
"I was extremely disappointed to get out with us needing that one run to get us promoted, but I was just glad I contributed to that total. I feel that I'm now in the history of Worcestershire County Cricket Club because neither my dad (Damian) or grandad (Basil) captained the team or won promotion."
Only 29 overs were bowled on the second day, and Yorkshire were 24 without loss in their reply when bad light stopped play just before 1.30pm. Rain followed, and umpires Steve O'Shaughnessy and Surendiran Shanmugam called play off just before 3pm.
Barring any last-minute points deductions for slow over-rates or disciplinary issues, Worcestershire will be playing Division One cricket for the first time since 2018 next summer.
Ironically, the last time they were promoted to the Championship's top division, in 2017, it also happened on September 27.
On that occasion, it was because rivals Northamptonshire dropped points in a match against Leicestershire.
This time, D'Oliveira's side were able to achieve the feat without the need for help from elsewhere and they will accompany Durham in going up.
On-loan Essex seamer Ben Allison also contributed a crucial career-best 75 off 114 balls and shared in stands of 77 for the sixth wicket with D'Oliveira and 79 for the eighth with Joe Leach as the county fell just short of 400.
Dom Bess impressed with 3 for 55 from 21 overs of off-spin for Yorkshire, claiming two of those wickets on day two.
New-ball seamer Milnes also struck twice and Matthew Revis once.
The day's first act was for D'Oliveira to move from 90 overnight to a superb century off 199 balls.
It was the captain's first century for his county since June last year, but he was denied the fairytale of hitting the promotion-clinching runs when struck on the back pad by Milnes.
That allowed left-arm spinner Baker to be the man, but he miscued the very next ball to mid-on off Milnes as Worcestershire slipped to 301 for 7 in the 86th over. Yorkshire, incidentally, had taken the new ball at the start of play.
Further success came for Bess after Allison had reached his fifty off 87 balls.
He uprooted Allison's off-stump with a yorker - 380 for 8 in the 100th - before wrapping up the innings by getting Leach caught at short fine-leg following a top-edged slog sweep.
Just a couple of balls earlier, Leach had hoisted him over long-on for six in a belligerent 36.
Sandwiched in between the two Bess wickets, Matthew Revis had Ben Gibbon caught behind.
While the first half of the morning was played under sunny skies, the clouds rolled in for the second and Yorkshire started their reply under the floodlights inside the session's final half hour.
They started confidently through Adam Lyth and Finlay Bean - both are within 50 runs of 1,000 for the season in the Championship - but were denied the chance to push on because of the weather.
Yorkshire have now lost circa 1,850 overs to the weather in Championship cricket this season.
This, however, was Worcestershire's day, and afterwards D'Oliveira admitted that the real challenge was to go one better than the team of 2017, and secure their top-flight status next season.
"It's pretty raw at the minute, but if you look in the past we've gone up and come back down. The challenge is to go up and stay up," he said.
"It's something myself and Alan Richardson (coach) will sit down and discuss over the next few weeks, and we'll try and prepare as well as we can going into next year."