A half century from Richard Wear helped Harden to a season best 225-8 and they looked favourites when Guiseley were struggling at 53-3.
But a 154-run stand between Peter Towner (101) and Dave Pennett (66) put the home team back on track until two quick run outs left them needing 10 to win off the final five ball and they fell just short despite Reeve’s efforts.
John Inglis (52) went past the half century mark for the seventh time in 12 starts and with Mitch Farag (41) and Yassar Ali (46no) steered leaders Beckwithshaw to victory over Steeton.
That leaves them 17 points clear of Burley, who needed a 73-run stand between Danny Bryan (29no) and Richard Brook (38) to clinch victory over Pool.
Alex Robinson (85no) guided Kirkstall past third-placed Otley’s 157 total in which Stewart Smith carried his bat with 77 not out, while half-centuries from Chris Wynd and Lewis Bolton and Robbie Miller’s 45 not out clinched victory for Ben Rhydding over Collingham.
Sajad Ali (5-44) and Will Liddle (3-24) restricted Follifoot to 174-9 and Ryan Nicholson (52) led Bilton’s successful run chase.
Jonathan Tattersall hit a century in Division Two leaders Knaresborough’s 205 in which Brett Kinsey took 5-52. Andrew Bourne (86no) and Sean Kirkley, who smashed 32no in 19 balls, grabbed the win for Tong Park Esholt to keep them in the promotion race.
Ryan Gladwin (72) and Andrew Doidge (5-56) starred as Rawdon overcame Colton to climb above Knaresborough.
Harry Neilson (95) and Alex Bailey (88) made sure Ilkley kept in touch with the front-runners by beating North Leeds. Thackley are also in hot pursuit, their 257-6 was too good for struggling Bardsey. Majid Khan (69), Yasser Ali (66) and Paul Naylor (53no) were the main contributors.
Phil Atkinson (109) and Michael Abbott (92) put on 216 as Green Lane passed Calverley’s 257-8, while Bolton Villas fell just short of Adel’s 236-7 and had to settle for a draw.