Josip Brekalo advanced and Wales did not close down the space as he freed Bruno Petkovic, who cleverly laid the ball into the path of Vlasic and he precisely fired home via the inside of the post.
A heavy collision between Domagoj Vida and Daniel James gave Wales even more to fret about, with James remaining on the field, but looking groggy after a heavy landing.
The challenge was almost exactly replicated after the interval when Petkovic crashed into Ethan Ampadu who landed awkwardly. It was something of a surprise the match finished with 22 players on the field.
The challenge on Ampadu saw Petkovic booked – he was one of eight – but arguably the punishment could have been stronger for a late arrival that would have most likely resulted in a red at the Rugby World Cup in Japan.
Ampadu could not continue while James at least looked to be fully recovered in the second half, though he shot at the near post when he should have fired across goal with Wales’ first foray forward after half time. Dominik Livakovic was able to smother at the second attempt.
Right-back Tin Jedvaj fired just over in the second half, but Croatia largely had plenty of possession without looking like finding a winner.
Davies the creator as he wins golden cap
Wales’ difficult start could have been even worse on 12 minutes but Wayne Hennessey saved Ivan Perisic’s flicked header after Petkovic’s inviting cross was misjudged by Ben Davies.
It was a tough moment for Davies as he celebrated becoming the 41st Wales player to reach 50 caps.
Still feeling his way back from summer hernia surgery and currently playing second fiddle at Tottenham Hotspur to Danny Rose, Davies picked the perfect moment to ignite his season with a brilliant assist for Bale’s leveller in first-half stoppage time.
The left-back rampaged forward and just got his foot to the ball as Mateo Kovacic looked for a free kick that never arrived.
Davies keept his composure to slide a pass into the penalty area. The delivery was perfectly weighted for Bale, who collected brilliantly to settle himself and shoot across Livakovic into the bottom corner of the net.
It was a night where clear chances were at a premium and Wales could not afford to over-commit in pursuit of a winner in a tense second half.
The night ended on a slight note of disappointment for Wales with Joe Allen receiving a late yellow card that will mean he is suspended in Azerbaijan, but they deserve credit for containing Croatia.
MAN OF THE MATCH: Gareth Bale
Bale continues to inspire an entire nation as he hits top form in the environment where he feels comfortable and appreciated. Scored a classic Bale goal and always gave Croatia a cause for concern until he limped through the last few minutes with Giggs later citing cramp as the Real Madrid star’s problem.