Ryan Giggs saluted "fantastic" Neco Williams after the Liverpool defender snatched a last-gasp winner in Sunday's 1-0 victory over Bulgaria.
Giggs' side were well below their best for most of the League B, Group 4 tie, but 19-year-old Williams came off the bench to break the deadlock with a header deep into stoppage-time at the Cardiff City Stadium.
Williams' first goal in professional football made it four successive wins in all competitions for Wales.
Following their 1-0 success in Finland on Thursday, Giggs' men stay top of the group and are now unbeaten in eight matches dating back to June 2019.
Of the teams who qualified for Euro 2020, none scored fewer than Wales, who struck just 10 times in their qualifying campaign.
That lack of firepower was a problem for long periods against stubborn Bulgaria, but right-back Williams finally opened up their massed defence on his home debut.
After a promising season with Premier League champions Liverpool, Williams' match-winning cameo rewarded Giggs' faith in a youngster who has a bright future, even if he has to serve as back-up to Trent Alexander-Arnold at Anfield.
"Neco came on the other night and he was fantastic, and he was the same today," Giggs said.
"He's got loads of quality, he's got confidence in his ability, and he's brought new energy to the group, and he showed that in focused little cameos in both games.
"I was umming and ahing whether to start him today because of the performance he put on the other night, but he came on and not only his goal but his overall performance was fantastic."
Clearly determined to frustrate the hosts with their cautious approach, Bulgaria had a rare chance when Galin Ivanov's curling shot deflected narrowly wide off Connor Roberts.
It didn't help the home side's cause that Gareth Bale was well short of the drive and sharpness that can only be gained from regular playing time.
Captain Bale barely featured for Real Madrid last season after the coronavirus hiatus as his strained relationship with their boss Zinedine Zidane left him frozen out.
Bale played just 45 minutes in Helsinki and two games in less than 72 hours was a big ask for the 31-year-old given his match fitness.
His struggles were summed up by a tame free-kick that never threatened to test Georgi Georgiev.
Looking to spark his side into life, Giggs sent on Hal Robson-Kanu as the West Bromwich Albion forward made his first appearance for three years after reversing his international retirement.
Manchester United winger Daniel James linked well with Brooks to create a sight of goal, but his powerful long-range strike was too close to Georgiev.
James returned the favour moments later, feeding Bale's pass to Brooks, who hit the top of the crossbar with his left-foot shot.
Wales' late pressure was rewarded in the fourth minute of stoppage-time when Jonny Williams swung a cross to the far post and Williams powered his header past Georgiev.