Wales were already guaranteed a World Cup play-off place through their Nations League results last year.
But the aim was to secure second spot in the group – and the semi-final home advantage that could come with it – by taking at least four points from their final two qualifiers against Belarus and Belgium.
Roberto Martinez’s Red Devils were confirmed as group winners by beating Estonia 3-1 on Saturday night.
This night was about more than World Cup points, however, as Wales fans paid tribute to a player seen by many as the greatest in their history.
Bale received a rapturous reception from a Cardiff crowd who have witnessed so many of his magical moments since he became Wales’ then-youngest international in 2006.
That fresh-faced 16-year-old was an adventurous Southampton left-back – the start of a journey that took Bale further up the pitch and onto Tottenham and Real Madrid, where he has become arguably British football’s greatest-ever export.
In the 15 years since Bale has carried the hopes of a nation and become Wales’ record scorer with 36 goals.
There would be no addition to that total, not even a shot on goal, before he made way at half-time having looked well short of match fitness.
Wales fans will hope his withdrawal was purely a precaution and not another injury after spending two months on the sidelines following a hamstring tear.
Bale started in a side showing three changes from the one that had won 1-0 in Estonia last month.
Kieffer Moore, Wales’ match-winner in Tallinn, was suspended and Chris Mepham and Sorbal Thomas also dropped out as Davies and Williams came in.
Wales went into the game with no fewer than seven players in their matchday squad one yellow card away from suspension and missing the Belgium game.
In the event, Ethan Ampadu was the only player to receive a second caution and will miss out on Tuesday.
Sergei Chernik had been at fault for Bale’s last-gasp winner in Kazan two months ago and the Belarus goalkeeper carried on from where he had left off inside two minutes.
Davies’ volley from the edge of the area should have been safely gathered, but Chernik spilled it and the lurking Ramsey tapped home into an empty net.
Bale’s long throw almost punished Belarus when Roberts latched on the loose ball and fired just wide of the far post
But Wales did double their lead after 20 with another helping hand from the hapless Chernik.
Bale found Williams and the Liverpool full-back squeezed his shot in at the near post with Chernik fumbling the ball over the line.
Belarus were maybe fortunate not to be reduced to 10 men when Nikolai Zolotov jumped into Davies and caught him flush in the face.
Zolotov escaped with a yellow card and Wales remained in control for the rest of the half without worrying Chernik.
Bale failed to reappear for the second half and, with their captain off, Ramsey took the armband and also penalty-taking duties when Ruslan Yudenkov handled five minutes after the break.
The Juventus midfielder sent Chernik the wrong way for his 20th Wales goal, moving him past Craig Bellamy into sixth place on the all-time scoring list.
Williams almost added a brilliant fourth before Davies marked his 68th cap with his first Wales goal, the ball going in off his shoulder from a Harry Wilson corner.
Belarus substitute Artem Kontsevoi claimed a consolation three minutes from time, but Roberts had the last word as Wales scored more than four for the first time since beating China 6-0 in March 2018.