Merthyr Town 1, Frome Town 2
The Martyrs suffered their first Southern League home defeat of the season and slumped from second to fourth place in the Premier Division.
Visitors Frome Town twice went ahead and they held on to deny the home team.
Connor Roberts (24 mins) and Samuel Teale (67) were the Frome scorers at Penydarren Park, while Jack Compton replied for Merthyr.
The defeat is a blow to Merthyr promotion hopes, but they are still in the thick of the promotion chase.
Ashley Evans went close from a half volley and Eliot Richards saw his effort from 20 yards go wide, while Compton had a penalty claim turned down when a Frome defender, trying to clear, appeared to kick high and catch him on the head.
Frome also created chances and Curtis McDonald did well to clear one chance off the line.
Manager Gavin Williams sent on substitutes Ian Traylor, Corey Jenkins and Kyle Copp in a bid to change things, but this wasn’t their day.
In the closing stages Compton whipped in a cross from a free-kick, but McDonald’s header flew just over.
The next match for Merthyr is away at Biggleswade next Saturday (3pm).
Merthyr Town: O Davies, C McDonald, J Wright, S Barrow, A Evans, A Davies, E Richards (K Copp), K Reffell (C Jenkins), K McLaggon, R Prosser (I Traylor), J Compton. Subs not used: S Tancock, K Patten.