Club Captain Brett D’Oliveira and Kashif Ali have taken Worcestershire to the verge of clinching promotion to Division One of the LV=Insurance County Championship after a record-breaking stand against Yorkshire at Headingley.
Worcestershire will resume on day two on 280-5 and require 20 more runs to reach 300 and secure the two points, which will guarantee their place back in the top flight.
Kashif and D’Oliveira came together at 67-4 after a challenging opening session in bowler-friendly conditions when play eventually got underway at 12.40pm.
But they transformed the fortunes of the day for Worcestershire in breaking a 67-year-old partnership record.
Kashif and D’Oliveira surpassed the 144 for the fifth wicket against Yorkshire by Don Kenyon and Martin Horton at Chester Road, Kidderminster in 1956.
They batted superbly, with Kashif producing a series of magnificent strokes through the off side to underline his potential.
The stand was worth 155 in 43.5 overs when Kashif was dismissed just seven runs short of what would have been a richly deserved maiden hundred in Championship cricket.
D’Oliveira continued his excellent run of form in Championship cricket after scores of 90 and 46 versus Gloucestershire, 74 against Glamorgan and 63 off the Durham attack.
He completed 5,000 first class runs in his career when on 34.
By the close, he had moved onto 90 not out from 191 balls with 14 fours after adding a further unbroken 58 with Ben Allison.
Worcestershire were put into bat on a green-tinged pitch by Tykes captain Shan Masood.
Ben Coad posed a threat with the new ball, and Gareth Roderick (5) was caught low down at third slip.
Azhar Ali (4) then took a stride forward to Coad but only succeeded in edging to second slip.
Jake Libby, who had passed 1,000 runs for the season against Durham, battled his way to 32 before he was lbw to a delivery angled in from George Hill.
Jack Haynes (14) pushed hard at Hill and was pouched at third slip, again low down, with Worcestershire 67-4, in the 20th over.
But Kashif and D’Oliveira counter-attacked effectively.
Kashif benefitted from a series of flowing drives, several of them at the expense of Jordan Thompson, which raced away to the boundary.
D’Oliveira also scored freely as Worcestershire reached 130-4 from 36 overs by tea.
Kashif completed an excellent half century off 62 balls with nine fours when he turned Thompson on the leg side for a single.
D’Oliveira cut the same bowler to the ropes, and a square drive brought him another boundary at the expense of Matthew Revis as he moved past 600 first class runs for the summer.
He reached his fifty from 78 deliveries with an exquisite cover drive for his 11th four at the expense of Thompson, and it also brought up the century stand with Kashif from 143 balls.
The fifth wicket pair continued to flourish, and Kashif played the cover drive to perfection with a boundary off Dom Bess after spin was introduced.
D’Oliveira survived one sharp chance on 63 when Adam Lyth failed to hold onto an edge at slip off Bess.
Another regal cover drive for four off Matt Milnes by Kashif set the new partnership record.
He looked set to complete his hundred when, on 93, he fell to a low caught and bowled chance taken by Bess.
Kashif struck 15 fours in his 131-ball innings.
The first bonus point was collected when new batter Allison pulled Revis to the boundary.
All-rounder Allison again showed his worth with the bat as he helped D’Oliveira bring up a half century stand from 65 balls.
The floodlights came on during the latter stages of the day, and the sixth wicket pair were content to negotiate the final few overs safely.