It was not until the 88th minute that the Linnets were out of the running for at least a point in their muddy Merthyr confrontation.
And then it had to be a penalty after defender Jimmy Wilson had pulled bustling Paul Caviel as he was about to shoot.
Ian Dockery did the necessary from the spot.
Up until then it had been a goal each - a score which would have summed a difficult, scrappy game in far from perfect conditions.
But even after that score, both sides put in some remarkably determined efforts in the dying minutes of a second half which lasted for 51 minutes.
There was one lengthy stoppage in the second half, when Lynn team boss Keith Rudd was bundled down heavily and it took several minutes before he could be revived.
It was Lynn who took a 15th minute lead after their defence, especially Phil Ringwood in goal and Johnston had soaked up constant pressure until then. David Goose put the visitors ahead with a well-placed, confident left foot shot after the hoe defence had been stretched following a bad kick out by keeper Don Payne and an equally had clearance by defender Chris Holvey.
Ringwood had been the visitors' saviour in the first half, but he had no chance with a close range, low diving header from Pratt only a minute from half time.
Lynn fought hard, but had to concede the double to the Welsh side who are still unbeaten at home.
Three players were booked - Merthyr defender Richard Evans and Lynn's Trevor Moden for dissent and Richard Johnston for a late tackle on Ray Pratt, the Merthyr and Southern League top scorer.
Before his injury, Rudd had seen enough to be pleased with Lynn's defensive qualities.
"We soaked up a lot of pressure and our back four did remarkably well to frustrate Merthyr. Jimmy Wilson and Richard Johnston were very authoritative and we limited Merthyr to few shots.
"Merthyr did have perhaps 60 or 70 per cent of the game, but we still had half a dozen clear chances to score ourselves although we were not so sharp going forward."
There was a diversion of opinion over the penalty incident - which Rudd himself did not see.
Our Merthyr correspondent took the view that Caviel was brought down as he was about to have a clear shot at goal; Lynn defenders thought that Caviel's own momentum took him down, especially as he was leaning on Wilson, and they felt it was very close to the by-line.
|Merthyr: Payne, Evans, Ingra, Holvey, Rosser, Docherty, Thomas, Morgan, Pratt, Caviel, Leniham; sub Fleet.
Lynn: Ringwood, Wilson, Wright, Johnston, W Rider, Watts, Goose, McManus, Wiles, Moden, Rudd; sub G Rider