Castleford relinquished top spot in the standings as they suffered a heavy defeat at North Marine Road, Scarborough’s Ben Elvidge (50) scoring a third consecutive half-century while sharing a partnership of 70 with Breidyn Schaper (81) who had already added 102 with Cian Dickinson (55) for the second wicket.
James Wainman crashed 34 off 14 balls and then took the first three wickets as the visitors looked to chase the hosts 257-6.
There were also three wickets for Elvidge (3-16) and by the time top scorer Connor Hyde (38) was out the result was beyond doubt and a 132-run loss ended the last remaining unbeaten record in the division.
The game of the day in the York League Premier Division took place at Clifton Park where Alex Liley (101) and Tom Norman (105) made centuries for their respective sides, both sides scored more than 270 and just five runs separated York and Folkton & Flixton at the end of an absorbing contest.
Skipper Tom Norman and Will Hutchinson shared a stand of 166 either side of which Sam Backhouse (6-49) picked up six wickets as the visitors were dismissed on the final ball of their 50 overs for 279.
Nick James (93) and Liley (101) responded with a partnership of 152 for the hosts but after both were dismissed by Rich Malthouse (5-47) the chase lost some of its momentum and finished with the score on 274-9 leaving both teams feeling they were within touching distance of victory.
Driffield Town 2nds overcame visitors Scarborough 2nds in an unusually low scoring Division One East encounter at Kings Mill Road.
The home side had James Barron (4-40) to thank, three of his four wickets accounting for top order batters, as the visitors were reduced to 72-7.
Ryan Hargreaves (39) led something of a recovery as the final three wickets more than doubled the total to 148 all out.
Opener Mark Clarkson (39) held firm as the hosts stumbled in their reply before Jon Vodden (23no) and Muhammad Hamza Khan (27no) got them over the line five wickets down.