Lancashire 167 for 6 (Livingstone 69, Croft 58, Root 2-25) beat Yorkshire 160 for 6 (Root 64) by seven runs
Joe Root's superb all-round display was not enough to prevent another Roses Vitality Blast defeat for Yorkshire as Lancashire qualified for the quarter-finals with a thrilling seven-run win at Emirates Old Trafford.
The England Test captain's 2 for 25 from four overs of offspin helped to stymie a blistering Lancashire start at 132 for 1 in the 15th over, with them ending on 167 for 6. Root then hit a memorable third fifty in four North Group innings this summer, 64 off 39 balls with eight fours and a six, only for the Vikings to slip from 115 for 1 after 13 overs to 160 for 6 after 20, failing to get 12 off the last over.
Lancashire strengthened their second place in the North with a fifth win from eight games, while Yorkshire are now out of contention having lost their last four. Yorkshire are still without a Blast Roses win since August 2017.
Lancashire opener Liam Livingstone top-scored with 69 off 43 balls and Steven Croft almost matched him with 58 off 45, but Root contributed significantly to the loss of five wickets for 16 runs.
Twenty four hours earlier, on the same pitch, he returned a golden duck and two wickets in England's ODI decider against Australia.
Second-wicket pair Livingstone and Croft shared 130 - their side's record partnership in Blast games versus Yorkshire. They united for 14.1 overs after the early departure of Alex Davies, caught behind off Duanne Olivier with the third ball of the first domestic match on this ground this summer.
The second-wicket pair were not without fortune. Inside the Powerplay, there were three lbw appeals from the spin of Adam Lyth and Dawid Malan which all looked out. The first of those, with Livingstone not yet in double figures against Lyth, was hardly appealed for.
Livingstone and Croft shared all seven sixes in the innings; Livingstone reached his fifty first off 34 balls before Croft's came off 39.
Yorkshire employed five spinners in their seven-man attack, including Root and left-arm wrist spinner Sam Wisniewski, an 18-year-old debutant who bowled two overs for 15.
With five-and-a-half overs remaining, Lancashire were eyeing close to 200. But then came the quite remarkable collapse of five wickets for 16 runs, including two wickets apiece for Root and seamer Jordan Thompson.
Thompson had Livingstone caught at long-on at 132 for 2 in the 15th over before Root had Croft caught at short fine-leg sweeping. In all, Lancashire only added 35 runs for the loss of five wickets in the final 33 balls, with 13 overs bowled by spin through an innings which saw no other home batsman reach 20.
Lyth viciously cut Luke Wood for six over backward point in the third over of Yorkshire's reply, only for Malan to miscue a pull against Danny Lamb to mid-on in the fourth as the score fell to 24 for 1.
Root then pulled Wood for six over midwicket in the fifth over and also added four boundaries in his first 12 balls, scoring 28 out of 58 for 1 after six overs of Powerplay. He continued to dominate in classy fashion, helping reach 92 for 1 after 10 overs with 46. Lyth had provided impressive support with 32.
The pair went on to share 91 inside 10 overs before a White Rose collapse to match Lancashire's saw Lyth, Root and Will Fraine all run out coming back for two and Harry Brook trapped lbw as the score fell to 148 for 5 in the 18th.
The target became 19 off two overs, with Matthew Parkinson getting Thompson caught at long-on before Saqib Mahmood defended 12 off the last against Jonny Tattersall and debutant Matthew Revis.
