Wales' winning habit continued with a 1-0 victory over Bulgaria as Neco Williams scored a dramatic stoppage-time header in Cardiff.
Liverpool teenager Williams, sent on as a 65th-minute substitute, met Jonny Williams' cross at the far post in the fourth minute of injury time.
It was the 19-year-old full-back's first goal in senior football on the back of his breakthrough season at Anfield.
The Dragons had opened their Nations League campaign with a 1-0 triumph in Finland on Thursday when Ryan Giggs' side made light of several notable absentees.
It was a third consecutive win for Wales on a seven-game unbeaten run, but Gareth Bale and company struggled to find the key to unlocking Bulgaria.
Bale, who has been out in the cold at Real Madrid, completed 90 minutes for the first time since January 4 but the country's record scorer could not add to his 33-goal tally.
The closest Wales – who kept a fourth consecutive clean sheet – had come to a goal before Williams' late intervention was when David Brooks struck the woodwork 16 minutes from time.
Brooks featured in a Wales line-up for the first time since June 2019 after missing most of last season following ankle surgery.
The Bournemouth forward was joined by Manchester City midfielder Matthew Smith, with Dylan Levitt and Jonny Williams dropping out from the side which had won in Finland.
Bulgaria were without several key players, including captain Petar Zanev who was injured during Thursday's 1-1 draw with the Republic of Ireland in Sofia, and had managed only one win in their previous 15 games.
That poor run of results had seen them slip down to 59th in the FIFA world rankings, 36 places lower than Wales in 23rd spot.
The last meeting between the two nations in October 2011 had been played at a deserted Vasil Levski Stadium as the home fans boycotted the game following a dispute with the Bulgarian Football Union.
Bale was the match-winner on that occasion and the Real Madrid star wore Wales' armband this time at a Cardiff City Stadium clash played behind closed doors because of the coronavirus pandemic.
Bale's heavy touch from a Kieffer Moore knock-down denied him an early shooting opportunity but neither side fashioned chances in the opening quarter.
The first sight of goal came after 25 minutes when Galin Ivanov was picked out by a delicious diagonal pass and his fierce shot was deflected wide by Connor Roberts.
Wales did not produce anything of note until the half-hour mark when a neat interchange between Brooks and Bale ended with the latter having his effort blocked.
The heavens opened to provide a slicker surface but both teams were still intent on shifting the ball backwards and sideways rather than risk a forward pass.
Wales did manage the first shot on target after 43 minutes when Bale drove a free-kick straight at Georgi Georgiev, although the Bulgaria goalkeeper collected comfortably on his line.
Brooks was off-balance moments later as he skewed a shot wide to bring to an end 45 minutes of forgettable football.
Wales were showing signs of improvement when Hal Robson-Kanu, having reversed his decision to retire from international football, replaced Moore just after the hour to make his first Dragons' appearance since October 2017.
Birsent Karagaren headed over as Bulgaria launched a rare attack but goal-bound attempts doubled at the other end as Daniel James played a one-two with Brooks to fire straight at Georgiev.
Brooks was about to be replaced by Jonny Williams when his last involvement saw him strike the angle of post and crossbar, and time was running out on Wales when Neco Williams emerged as the hero.
