Potters Bar's lead at the top of the Herts Cricket League Premier Division was cut to just two points from Radlett - as North Mymms and Welwyn Garden City kept their play-off chances alive.
The leaders lost by just one run to Mymms in a thrilling derby match at The Walk, their Welham Green rivals using the points gained to move back into the top four with three games to go.
The visitors won the toss and had no hesitation in batting first.
They got to 256-8 in their 50 overs with Hamza Qayyum getting to his first half-century of the season on 54 with Chanaka Ruwansiri joining him after making the batting look easy.
Bar had been in touch at 45-2 until the the pair got together and put on 85 for the third wicket.
But when Ruwansiri was dismissed for 69, James Scott trapping him leg before, the home side got their tails up again and sent Mymms from 169-3 to 181-6.
But Imran Qayyum (46*) and Dharmajsinh Jhala (24) stretched the score in the closing stages with 59 for the seventh wicket.
Two late wickets from Jigar Mehta (3-61) meant Bar confirmed at least a second place finish this year and a home tie in the play-offs. Scott led the bowling figures with 4-34.
The reply stuttered in the early going with Bar 37-2 after 12 overs and even the top scoring Reece Hussain and Steve Gale couldn't find any rhythm in the wake of excellent bowling and fielding from Mymms.
Their departures left Bar 84-4 and a further wicket meant Bar needed a highly unlikely 148 from 90 balls.
But Luke Chapman and Charlie Scott had other ideas. The pair put on 50 in 35 balls and when Scott went for 47, the equation was 93 needed in 54.
Dan Pett joined Chapman and they smashed 22 in eight balls before arguably one of the catches of the season saw Ruwansiri run 20 yards and dive full length at deep midwicket to hold on.
It left Chapman on 49 from 27 balls with Bar now needing 72 in 46 balls.
Successive sixes plus three fours and a maximum in his first 12 balls saw Anmol Maheshram keep the pace going and with two overs to go the position had swung firmly in Bar's favour, leaving them just eight adrift.
He scored seven in the opening two balls of the over but then Teddy Duke and Mehta were out in successive deliveries and Bar were all out for 255 with Maheshram stranded on 47 not out from 18 deliveries.
Simeon Cohen and Imran and Hamza Qayyum all got two wickets each for Mymms.
Welwyn meanwhile defeated Totteridge Millhillians by four wickets at Digswell Park.
They stay seventh but are just 12 points off the play-offs and Mymms in fourth.
They bowled the visitors out for 183, Owais Shah taking 3-8 in three overs, and the former England man led the reply with 54 not out as they got home in the 37th over.
Dan Blacktopp (36), Alex Chalker (28) and Dylan van der Westhuizen (24) were also among the results.
Knebworth Park secured promotion from Division Three A with a 187-run victory over North Enfield - their eighth in a row.
It leaves them 119 points clear of third place with three matches left but still seven adrift of leaders West Herts who also continue winning.
Openers Louis Champion (68) and Josh Roseberry (65) led the way as Park finished on 321-9, Archie Stephens (54), Charlie Randall (37) and Kobie Richmond (27) also contributing.
Randall (3-24) and Alex Richmond (3-26) were the pick of the bowlers for Park who wrapped things up inside 32 overs.
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