Spain produced a Cardiff masterclass to stun Wales and send a warning shot to Nations League rivals England.
Luis Enrique’s stylish side strolled to a 4-1 victory on a night when Wales returned to the 74,500-capacity Principality Stadium for the first time in seven-and-a-half years.
Sam Vokes headed a consolation a minute from time but it was a sobering evening for Ryan Giggs’ side ahead of their Nations League game against the Republic of Ireland.
After half-an-hour, statisticians were thumbing through the record books to discover Wales’ heaviest loss was a 9-0 defeat to Scotland in 1878.
It did not quite get to those proportions as a raft of replacements took the sting out of Spain’s attacking edge, but it was still Wales’ heaviest defeat since a 6-1 thrashing away to Serbia in September 2012.
Wales had not played at the home of Welsh rugby since losing a Euro 2012 qualifier to England 2-0 in March 2011.
The attendance of 50,232 justified the Football Association of Wales’ decision to move the game from the Cardiff City Stadium, although it was not a switch that went down well with die-hard supporters.
Spain appear to be in rude health after the disappointment of their last-16 exit at the World Cup last summer, scoring 12 goals in Enrique’s three games in charge.
Almost from the first minute this was a harsh lesson for the hosts who were a mixture of youth and experience, but without their talisman Gareth Bale.
Giggs is hoping that Bale will be involved in Dublin on Tuesday and, on this evidence, Wales certainly need him.
Both managers gave a nod to next week’s Nations League action in terms of selection.
Enrique made six changes from the side which crushed World Cup finalists Croatia 6-0 last month, but David de Gea and skipper Ramos were both in the starting line-up three days ahead of England’s visit to Seville.
Giggs showed Spain respect by altering his usual formation and playing three central defenders, but Wales were undone as early as the eighth minute.
Hennessey’s poor punch fell to Jose Gaya and, when the Valencia defender turned it back into the area, there was Alcacer to find his spot firmly.
Spain doubled their lead after 19 minutes and it was far too easy.
Suso’s free-kick evaded a dozing Wales defence for Ramos to embrace the freedom of Cardiff and head past an unguarded Hennessey.
That statue-like defending was visible again after 29 minutes when Wales passed up the opportunity to clear the ball on a couple of occasions.
The ball looped into the air and, with Wales seemingly distracted by an injured Spain player lying prone in the penalty area, Alcacer ran on to dispatch a merciless volley.
There was brief cheer for Wales when Ethan Ampadu met Harry Wilson’s corner and his header clipped the outside of a post.
It almost got worse for Wales as Suso cut on to his left-foot and curled the ball against the crossbar.
Aaron Ramsey tested substitute goalkeeper Kepa Arrizabalaga and, with half-time arrival David Brooks adding urgency to the Wales attack, Sam Vokes was stopped by a last-ditch tackle.
Bartra rose superby from a 74th-minute corner to deflate Wales even further before their crunch trip to the Republic.
But Wales had the last word when the impressive Brooks crossed and Vokes directed his header into the corner of Arrizabalaga’s net.