Derbyshire 239 for 7 (Johnson 79, Wardlow 3-60) beat Yorkshire 238 for 7 (Gale 51, Ballance 47)
Richard Johnson's maiden one-day half century spearheaded an impressive Derbyshire recovery that carried them to a three-wicket victory over Yorkshire with 14 balls to spare in the Clydesdale Bank 40 at Chesterfield.
Johnson, a wicketkeeper on loan from Warwickshire, survived two dropped catches to score 79 from 74 balls after Derbyshire had been 56 for 4 chasing Yorkshire's 238 for 7.
Itr was a disappointing comeback from a hip complaint for Yorkshire's captain, Andrew Gale, who made 51 on his return as he tuned up for the Friends Life t20 quarter-finals.
Yorkshire looked favourites when Derbyshire lost early wickets but Johnson shared a stand of 80 in 11 overs with 20-year-old Alex Hughes, whose unbeaten 37 guided Derbyshire home.
The teams observed a minute's silence in front of the pavilion before the game in memory of Don Wilson, the former Yorkshire and England left-arm spinner, who died in a York hospital on Saturday at the age of 74.
Gale was given out hit wicket after he trod on his stumps trying to work Durston through midwicket. The former Yorkshire slow left-armer David Wainwright also restricted Yorkshire, although Jonny Bairstow launched him over the hospitality tent for six and then drove Chesney Hughes back over the sightscreen.
Just when the England batsman was threatening to take the bowling apart, Mark Turner plucked out his middle stump with a fast and full delivery at the start of the 31st over.
Gary Ballance, with 47 from 42 balls, took Yorkshire past 200 but it was Richard Pyrah who did the damage by smashing Jon Clare for three consecutive sixes at the starty pof the penultimate over before holding out at long on.
Yorkshire's total looked even better when Usman Khawaja was caught behind for a duck off the third ball of Derbyshire's reply. Mitchell Starc then cut one back to bowl Chesney Hughes for 20 and in the next over Durston top-edged Iain Wardlaw to short fine leg.
When Starc cleaned up Dan Redfern in the eighth over, Derbyshire were struggling but two dropped catches by Azeem Rafiq before Johnson reached double figures allowed them to recover. They added 67 in 12 overs before Wayne Madsen chipped back a return catch to Adil Rashid but Johnson kept Derbyshire on track.
He drove Wardlaw for six and dispatched Pyrah into the crowd before he carved Wardlaw to Pyrah at cover with 18 needed, but Alex Hughes showed composure in only his seventh senior game and drove Starc for the winning boundary.