Ten-man Witton Albion held on to become just the second team to win in the league at Farsley this season, as they took a 1-0 win.
The visitors took advantage of sloppy defending as Rob Hopley put them ahead just after the break.
They then had Matty Devine controversially sent off as he gave away a penalty but Farsley’s Ben Atkinson couldn’t convert, and Albion held on to take the three points.
Farsley manager Adam Lakeland was frustrated with his side’s performance, as they squandered top spot following Warrington’s late equaliser in a 3-3 draw with Nantwich.
He said: “I thought we were average at best in the first half. In the second half we conceded an awful goal, there’s no other word to describe it really.
“Their keeper made a good save from the penalty and to be fair we kept knocking on the door, but we found it hard to break down a really resilient team.”
The visitors had a few good opportunities early doors, with James Foley first firing straight at the wall from a free kick on five minutes, before Danny Ellis miss-cued a header high into the box on 10 minutes, but Hopley’s free header went wide of the upright.
Farsley’s best chance of the opening half came on 16 minutes as Chris Atkinson and Dave Syers both had shots charged down.
There was concern for Celts right-back Lewis Turner on 25 minutes when he slipped when attempting to clear the ball. He was stretchered off the field with a knee injury and later hobbled out of the ground on crutches.
There were few chances for either side for the rest of the half, which was seriously lacking in quality.
Witton were quick out of the traps in the second half and after a moment’s hesitation between the Farsley defenders, Hopley picked up the ball and shrugged off Adam Clayton before rounding Kyle Trenerry to fire home on 47 minutes.
Then three minutes later, Farsley were handed a penalty after Nathan Cartman was pushed by Devine, as he went to head the ball home. Referee Oliver Noonan decided it was worthy of a red card and Witton were to see out the final 30 minutes with ten men.
Substitute Ben Atkinson was unable to convert the spot kick though, as goalkeeper Greg Hall made a good save to his right.
The Celts peppered the visitors’ goal but against a strong Witton side who have only conceded 31 times in the league this season (the second lowest in the competition) it was always going to be an uphill battle.
Syers had a couple of good chances, firstly heading wide from Will Hayhurst’s corner then unluckily seeing his shot from just inside the area, blocked by a team-mate on 89 minutes.
The Celts’ final chance of the game came in stoppage time as Danny Ellis’s header was thwarted by another good save from Hall.
Farsley Celtic (5-3-2): Trenerry, L Turner (B Atkinson 28), Hayhurst, Higgins, Ellis, Clayton (Baldwin 90), Syers, C Atkinson, Spencer, Cartman, Parkin (Walker 61).
Subs not used: Bower (GK), Bett