Worcestershire need four more wickets to seal promotion after dominating the second day of the Specsavers County Championship clash with Durham at New Road.
First Ravichandran Ashwin hit a superb 82 and Ed Barnard a career best 75 as Worcestershire claimed three batting points in totalling 335 all out in their first innings.
Then the County’s attack made inroads with skipper Joe Leach and Josh Tongue picking up two wickets apiece as Durham closed on 142-5.
If Worcestershire take a total of nine Durham wickets inside the first 110 overs then they will be promoted, having accrued the six bonus points required at the start of the game.
But promotion could arrive sooner than that if Northamptonshire, who ended day two on 199-8 away to Leicestershire, are bowled out before they get to 300 in 110 overs.
Indian all-rounder Ashwin came to the wicket at 113-4 after the early loss of Joe Clarke and had lifted the total to 284-7 when he was dismissed.
Worcestershire were eventually bowled out for 335 in 90.2 overs.
Ashwin shared in half century stands with Ben Cox and Ed Barnard – who surpassed his previous best of 73 versus Derbyshire at Derby last summer – as once again the Worcestershire middle and lower order showed their worth.
Ashwin went to his fifty off 86 balls with four fours and looked in complete command and a calm presence at the wicket.
He reeled off some delightful cover drives but was also content to accumulate singles with the minimum of fuss.
Worcestershire resumed on 90-3 after a truncated opening day with Clarke unbeaten on an excellent 46 from 46 balls.
The England Lions batsman completed his third half century of the season – in addition to two hundreds – with a two through mid wicket off Graham Onions.
It came off 52 balls with eight fours.
Clarke added two more boundaries down to third man off Onions but on 65 he edged the former England paceman to Paul Collingwood at first slip.
George Rhodes battled away in making nine off 42 balls but the introduction of spinner Ryan Pringle resulted in him being lbw.
Ashwin and Cox adopted an aggressive but also sensible approach on a beautiful autumn’s day at New Road.
The partnership was worth 66 in 18 overs when Cox drove at Cameron Steel and was bowled for 30 by a delivery which came back into him.
New batsman Barnard swept Trevaskis for four to bring up the 200 and the first bonus point in the 59th over.
By lunch Ashwin had moved onto 47 and Barnard six out of 204-6.
Ashwin quickly reached his half century after the resumption with a cover drive for four at Steel’s expense.
The half century stand came up in 11.5 overs before Ashwin on 69 had a let off when he gave Trevaskis the charge and survived a stumping chance.
Barnard clubbed a full toss from Ryan Pringle for six as runs continued to flow before Ashwin was lbw to Trevaskis after hitting seven fours in his 130 ball knock.
The partnership with Barnard was worth 86 in 18.2 overs.
Barnard went onto complete his half century – his fifth of the season – off just 59 deliveries with one six and four fours and he and skipper Joe Leach secured bonus point number three at 300-7 shortly after the second new ball was taken.
Onions accounted for Leach (10) and Josh Tongue (10) before Barnard was last out, bowled by Mark Wood.
The Worcestershire new ball attack of Tongue and Leach soon got to work.
Tongue had Keaton Jennings (9) caught behind and bowled Jack Burnham (4) and then Cameron Steel (10) nicked Leach to give Cox his second catch of the innings.
Graham Clark and Paul Collingwood added 76 for the fourth wicket.
But Ashwin struck as Collingwood on 27 went to cut and was bowled and in the closing minutes of the day Clark (65) was caught and bowled by Leach off a leading edge.