Durham have won promotion to Division One of the County Championship despite not having a game this week.
Leicestershire's failure to earn any batting bonus points against Sussex means they can no longer surpass Durham's current points total of 198.
The north-east county need a maximum of five points from their last two games to seal the Division Two title.
Durham have been in Division Two since they were relegated over financial issues in 2016.
The three-time county champions finished fourth in Division One that season, but eighth-placed Hampshire were given a reprieve by the England and Wales Cricket Board - and Durham were also docked 48 points for the 2017 season.
With their success still sinking in, head coach Ryan Campbell is already thinking about next season's challenge of re-establishing Durham in the top tier.
"All we can do now is take and put this team where we think it belongs, and I'm extremely proud that this club is where it is now," Campbell told BBC Look North.
"We're not going to Division One just to survive, we're going to try to win the thing [title], I reckon there's a lot more exciting cricket to come."
Players bought into Campbell ethos
In reaching the top-tier, Durham have won six of their 12 Championship games so far this season, losing only once under Sunderland-born captain Scott Borthwick, who is in his second spell with the club.
They have the highest-scoring batter in the country in Alex Lees, who has 1,281 runs, including five centuries, and Matthew Potts and Ben Raine have each taken 51 Championship wickets.
"I took over a pretty good squad, a lot of hard work has gone into this team for a long time now, I came at the right time," coach Campbell added.
"We wanted to play a different style to what we had played, as an Aussie growing up with some great mentors, we kind of knew the way we wanted to play. That was always my vision but to get the guys to buy into it was going to be important but thankfully they've just embraced it.
"What we've seen is a group of talented blokes go about their business with the bat but just as importantly with the ball."
The current round of matches began with them 44 points clear at the top of the table.
It meant that only Worcestershire and Leicestershire could still deny them promotion - but would need maximum points from their remaining fixtures to reach a total of 202.
Worcestershire are also not involved this week - they will host Durham at New Road on 19 September.
But Leicestershire were bowled out for just 108 on day two against Sussex, conceding a first-innings deficit of 154, and even if they were to somehow turn the match around and win it, the maximum number of points they can now achieve is 197.
Analysis - 'Attacking cricket rewarded'
BBC Radio Newcastle commentator Martin Emmerson
These are very different times from the dark days of October 2016 when Durham were relegated from Division One by the ECB.
At the time they were among a number of county sides who'd got themselves into debt bidding for Test matches and upgrading their grounds.
The ECB bail-out was described as "saving first-class cricket in the north east" and while that may be partly true, it felt like the club had died at the time. Relegated with a 48-point deduction for the start of the 2017 season and a generation of some of the best cricketing talent in the country leaving to go elsewhere.
Durham were obviously responsible for some of the decision-making processes which led them down the road to trouble. They were also the victims of the banking crash. Their sponsor, Northern Rock, went bust and their preferential loans were called in.
I thought back then it would be at least five years before they rose again - and if you take out the two Covid seasons - it looks like it will be.
New head coach Ryan Campbell has been like a breath of fresh air. He wanted them to play attacking cricket and they have. They have won six games and gained maximum batting points seven times.. They now have 46 of those - the club record is 49, set in 2009 when they won the title unbeaten, and that tally looks in jeopardy.
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