Durham 157 for 3 (Collingwood 88*) beat Yorkshire 156 for 7 (Willey 40, McCarthy 3-33, Coughlin 3-34) by seven wickets
Yorkshire's hopes of a quarter-final place in the NatWest T20 Blast suffered another setback when they failed to complete the double over north group stragglers Durham at Chester-le-Street.
After the previous night's defeat by Derbyshire, Yorkshire made a hash of chasing Durham's 157 for 3, finishing on 156 for 7 after they appeared to be coasting.
The turning point came when man of the match Paul Collingwood followed his unbeaten 88 with a direct hit from deepish mid-off to run out Alex Lees for 29, ending a stand of 47 with David Willey.
When Willey lifted a catch to deep mid-wicket to depart for 40 it was left to Jack Leaning and Tim Bresnan to score 40 off the last four overs.
With 22 needed off two, Bresnan drove Paul Coughlin to long-on, but Leaning smashed the next two balls to mid-wicket for six and four before skying to extra cover.
With ten required, Usman Arshad began the last over with a wide, but Adil Rashid and Azeem Rafiq were unable to find the boundary and three were needed off the last ball.
Azeem swung and missed and they managed only a bye, giving Durham their second victory of the series by one run.
Collingwood continued his remarkable form by following his maiden Twenty20 century at Worcester on Sunday with his second highest score in the format.
That Worcester century had made him the oldest man to make a professional T20 hundred.
He appeared to be limping from early in his 54-ball innings, but his seven fours and two sixes provided nearly all the strokes of authority in an innings which would have foundered without him.
Michael Richardson contributed 32 to an unbroken stand of 86 and from 68 for 3 after ten overs Durham did well to set a competitive target.
Yorkshire looked well on course when Adam Lyth and Tom Kohler-Cadmore launched the reply with 35 off the first four overs.
The ex-Worcestershire man drove Barry McCarthy for a huge straight six, but the Irishman had both openers caught at third man off successive balls to give Durham hope.
Left-handers Lees and Willey accumulated steadily until Paul Coughlin brought himself on for the 12th over and Lees lifted his first ball over the stand at mid-wicket.
He was then run out and Sarfaraz Ahmed managed only six before miscuing to mid-wicket to give McCarthy a third wicket.
Collingwood kept it tight, conceding 26 in his four overs, and when Willey departed it left the rest with just too much to do.