Slazenger were looking to bounce back after a poor run of recent form but were left ruing a series of missed chances as they went down 1-0 the the bottom side Thirsk.
Things started brightly for the home team as they moved the ball well but were just letting themselves down with the final pass.
Ben Garside was controlling things in a reshaped midfield and Slazenger continued to dominate the possession with Rich Hutchins creating chances.
It came as a body blow to Slazenger as Thirsk scored from their only attack of note to go in at the break in the lead.
The second half was much the same with Slazenger dominating but not finding the final touch. Tim Carr found himself in a couple of good positions but the defence just did enough each time.
The Horbury side were in control right up to the final whistle but were left frustrated at their lack of ability to finish a game that should have been a comfortable win.
Slazenger will be looking to kick-start their promotion charge away to Halifax this week.