Daniel Alfei scored the only goal as Wales beat Montenegro in their European Under-21 Championship qualifier.
The result in Wrexham avenged Wales' 3-1 loss away in Montenegro in September and means Wales move level on six points with them in Group Three.
The game turned in the 57th minute when Aleksandar Sofranac fouled Wales striker Ryan Doble in the penalty area.
Alfei converted the spot kick to send Wales into Tuesday's home clash with the Czech Republic in good heart.
Wales started well, with Kieron Freeman firing just wide with a cross-shot inside the first minute.
Doble and Tom Bradshaw worried the visitor's defence with determined running and Radivoje Golubovic was booked for an early foul on Doble.
On 13 minutes Montenegro goalkeeper Pavel Velimirovic was fortunate to keep out a fierce 20-yarder from Swansea's Lee Lucas.
Jake Taylor and Bradshaw then combined at pace to produce a chance that Jake Howells volleyed over on the run, before Taylor headed over from Howells' angled cross.
Montenegro defended in numbers, stringing six men at times across the face of their box and aiming to catch the home side on the break.
But Wales maintained possession with neat, controlled passing, managing to create one more decent chance in the half when Bradshaw headed wide from Howells' deep cross.
Montenegro opened up more after the break, but it was Wales who took the lead on 57 minutes when the visitors conceded a needless penalty.
Sofranac pushed over Doble in the box when the ball looked to be going out of play. The defender was booked and Swansea's Alfei rammed home the spot kick.
Doble volleyed wide from a Bradshaw lay-off, but Montenegro almost equalised when Golubovic hit the inside of a post following a corner.
Bradshaw could have finished the contest with five minutes left after Doble had played him in, but Velimirovic produced a fine save to his left.
Wales managed to run down the clock for a deserved victory, with Swansea's Ashley Richards in outstanding form at the back.
Wales U21: Maxwell, Freeman, Richards, Lucas, Brown, Alfei, Jake Taylor (Bodin 79), Hewitt, Bradshaw, Doble, Howells. Subs Not Used: Cornell, Evans, Dummett, Stephens, Chamberlain, Ogleby.
Goals: Alfei 58.
Montenegro U21: Velimirovic, Radivoje Golubovic, Balic, Sofranac, Tomasevic, Nikola Vukcevic (Ivanovic 66), Stefan Nikolic, Dejan Bogdanovic, Kajevic (Mugosa 66), Rebronja (Radulovic 46), Seratlic. Subs Not Used: Agovic, Alic, Radunovic.
Booked: Radivoje Golubovic,Tomasevic, Kajevic, Sofranac.
Ref: Vladimir Vnuk (Slovakia).
Wales Under-21 squad vs Czech Republic: David Cornell, (Swansea City, on loan at Hereford United), Chris Maxwell (Wrexham), Daniel Alfei (Swansea City), Troy Brown (Rotherham United), Paul Dummett (Newcastle United), Kieron Freeman (Nottingham Forest), Ashley Richards (Swansea City), David Stephens (Hibernians), Billy Bodin (Swindon Town - on loan at Torquay United), Elliott Hewitt (Macclesfield Town), Jake Howells (Luton Town), Lee Lucas (Swansea City), Jonathan Williams (Crystal Palace), Tom Bradshaw (Shrewsbury Town), Elliott Chamberlain (Leicester City - on loan at Stockport County), Ryan Doble (Southampton - on loan AFC Bournemouth), Robert Ogleby (Heart of Midlothian on loan at East Fife), Jake Taylor - (Reading - on loan at Aldershot Town).