Hayes and Yeading United make their first visit to Penydarren Park on Saturday (3pm).
Middlesex-based Hayes, second from bottom and already relegated from the Southern League Premier, hold the key to Merthyr Town’s immediate future.
A Martyrs win in this final league match of 2016-17 would guarantee them a home tie in the play-off semi-finals, while anything less could see them having to travel.
Leamington have secured runners-up spot behind champions Chippenham Town, who are promoted automatically. The fixtures for the other contenders see fourth-placed Hitchin Town away at mid-table Basingstoke, while Slough Town, currently fifth, would be expected to beat Redditch United at home.
Hayes pay their first ever visit to Penydarren after being formed in 2007 from the merger of Hayes FC and Yeading FC.
Both of these clubs were previously members for many years of the Isthmian (Ryman) League), while Hayes spending six seasons in the Conference from 1996.
At the time of their merger both were in Conference South and despite some initial success leading to three seasons in what was then the Blue Square Premier were relegated last season from National League South.
The reverse fixture in September saw Merthyr’s biggest league win of the season with Kayne McLaggon scoring a hat-trick in a 6-1 win.
A change of management saw former Kings Langley management duo Paul Hughes and Richie Hanlon appointed in November followed by an overhaul of the playing squad with only three players now remaining from the game in September.
One of these is young striker Dylan Kearney, who is their second-highest scorer on six goals.
Ahead of him is Mitchell Weiss, who is on 13 including eight in League Cup ties, helping United to their place in the final which sees them away to St Ives Town next Saturday.
Hayes have earned two wins and two draws from their last six matches, suffering two defeats. They have only four away wins to their credit all season.
Merthyr’s Scott Tancock is a doubt following his injury at Redditch and this may see Kyle Patten play alongside Jarrad Wright in defence. Ian Traylor may be fit to return to the squad, while Curtis McDonald is still being assessed.
The match and ball sponsors TPS 360 Ltd of Caerphilly.
The match programme, priced £2 as usual, includes extra pages with a special article by Phil Howells to mark Ian Traylor’s 300th appearance and the conclusion of Phil Mack’s account of this season’s away trips and good cider guide
Premier Division – all teams play 46 fixtures
Top six only
Champions promoted automatically, next four qualify for play-offs.
Format for play-offs: 2nd v 5th, 3rd v 4th.
Pl GD Pts
1 Chippenham Town 45 +45 100
2 Leamington 45 +46 92
3 Merthyr Town 45 +46 86
4 Hitchin Town 45 +34 85
5 Slough Town 45 +28 84
6 Banbury United 45 +28 80
Southern League Premier Division fixtures on Saturday: Banbury United v Kettering Town; Basingstoke Town v Hitchin Town; Biggleswade Town v Frome Town; Cambridge City v St. Neots Town; Chippenham Town v St. Ives Town; Dunstable Town v Cinderford Town; King’s Lynn Town v Chesham United; Kings Langley v Cirencester Town; Merthyr Town v Hayes & Yeading United; Slough Town v Redditch United; Stratford Town v Dorchester Town; Weymouth v Leamington.