Record-breaking 15-year-old Matthew Fisher enjoyed a promising debut for Yorkshire but his side still lost to Leicestershire.
Fisher, at 15 years and 212 days, became the youngest post-war player to take part in a competitive county cricket match.
But Yorkshire's fledgling pace attack just failed to contain high-flying Leicestershire in their Yorkshire Bank 40 Group C match at Scarborough when the visitors reached their 259 target with five balls and three wickets to spare.
Injuries resulted in the Tykes playing four teenage fast bowlers, including York-born Fisher, who took 6-25 in a second XI match against the Foxes in midweek.
Also making his first-team debut was 17-year-old Ryan Gibson, while Ben Coad, 19, was playing in his second game and Will Rhodes, 19, his fifth.
The hosts set a total of 258-9 as Joe Sayers (58) and Liam Plunkett (53) did the bulk of the scoring.
Their total was boosted by 61 off the final five overs, with Plunkett plundering his half century with a whirlwind knock off 23 balls late in the innings
In reply, Fisher, who had scored 10 runs off four balls with the bat, bowled seven overs for 40 runs, trapping Shiv Thakor lbw for his first senior wicket, while Rhodes claimed wickets in consecutive overs, having Greg Smith caught behind for 58 from 51 balls, with seven fours and a six, and Ned Eckersley (24) caught in the deep by Adam Lyth.
Gibson also took a wicket and with the visitors at 189-7, the momentum had swung Yorkshire's way.
But Rob Taylor (48no) and Jigar Naik (22no) turned the tables with some positive batting in an unbroken eighth-wicket stand of 71 in eight overs to seal the victory.
Yorkshire have now lost five of their six outings in the competition and are above only the semi-professional Unicorns, who lost by 85 runs to Glamorgan.