England all-rounder Ben Stokes' unbeaten 90 could not prevent Durham losing their T20 Vitality Blast opener at Yorkshire by 44 runs.
Stokes, opening the batting, hit eight fours and five sixes but it was not enough as the Jets, chasing 201, fell short by 44 runs in the North Group encounter at Headingley.
Adam Lyth's 54-ball 92 not out, which included nine fours and three sixes, propelled the Vikings to 200 for three from their 20 overs.
He shared in an unbroken stand of 110 with wicketkeeper Jonathan Tattersall (53 not out), while Harry Brook weighed in with 44.
Ed Barnard hit four off the penultimate ball as Worcestershire beat Lancashire by five wickets in a tight finish at Old Trafford.
Captain Brett D'Oliveira remained unbeaten after hitting a crucial 37 for the Rapids, who were set a target of 189.
Keaton Jennings had been the mainstay of the Lancashire innings with 50.
In the South Group, Middlesex began with a three-wicket win over rivals Surrey at Lord's.
Paul Stirling's 66 from 36 balls got the hosts' pursuit of their 159-run target off to a fine start and Hilton Cartwright (38) steadied the innings after a middle-order collapse. James Fuller (18no) completed the job.
Rikki Clarke (50) top-scored in the Surrey innings.