Nobody could have seen this result coming.
Fulham, 14th beforehand and with one of the worst home records in the Championship, tore apart high-flying Huddersfield Town, who were seeking a fourth win on the road and 10th of the season in all.
With Norwich City suffering the same fate at Brighton and Hove Albion, David Wagner’s shell-shocked side remained third despite the heaviest defeat of his reign as head coach.
The boss doesn’t face a rebuilding job - Town have shown what they’re capable of too many times to say anything like that - but he does need to find solutions to a few problems which have emerged during a run of three defeats in four matches.
High on the list is sharper defending, particularly against set-pieces and crosses.
Town struggled to deal with them in their previous away game at Preston North End.
And a free-kick was behind the first goal, scored by Chris Martin, which rocked Town and provided the foundations for Fulham to take such a firm grip of this game.
After Tomas Kalas scored his side’s second, when Town again struggled to deal with a ball into their box, Sone Aluko took centre stage, supplying the crosses for the third, headed home by Lucas Piazon before the break, and fifth, driven in by Kevin McDonald.
In between the tricky former Hull City player won the penalty, for a foul by Christopher Schindler, which allowed on-loan Derby County man Martin to notch his second of this match and fourth in as many outings.
Wagner’s side also need to be sharper in front of goal.
Along with Sheffield Wednesday and Leeds United, their tally of 16 goals in 15 games is the lowest in the top half of the table, and leaders Newcastle United have notched twice as many as the Yorkshire trio.
And Town, while occupying a lofty position, have a negative goal difference.
WATCH: Huddersfield Town in fine voice at Fulham FC DESPITE 5-0 mauling
One of the many frustrations at Craven Cottage was that they created chances, but failed to take them.
With Town just one down, Nahki Wells was thwarted by right-back Ryan Fredericks as he shaped to shoot, then Tommy Smith headed wide.
And either side of the break, Harry Bunn headed just off target before Kasey Palmer was denied by keeper David Button as Fulham sealed a first clean sheet in seven and only a fourth of the season.
Wagner’s side might have been trailing by three, but a reply at that stage might just have shaken the hosts.
Instead, two goals in three second-half minutes meant Town were left on the ropes.
It was their worst defeat since Norwich won by the same scoreline at Carrow Road in December 2013 and Fulham’s first 5-0 win since that against Norwich in August 2012.
And it’s no exaggeration to say the home side could have scored more, because substitute Tim Ream should have made it six, only to head onto the roof of the net from close range.
It’s important to keep a sense of perspective, because there have been so many encouraging signs so far this season.
Town have 28 points from 45, just six less than a Newcastle side they beat at St James’ Park.
But it’s vitally important the bounce back when Birmingham City visit the John Smith’ Stadium this Saturday.
They did it at the expense of Derby County in the wake of the disappointing 3-1 setback at Preston.
And a three-point haul back on home turf, where Wagner’s side have won six out of seven, would restore some confidence going into the third international break of the season.
Town took a great and highly vocal following to the capital (2,743 supporters in a recorded gate of 19,858).
As the boss noted afterwards, they were far better than the team they follow.
Wagner demands his side are competitive in every contest, but sadly in this one, they weren’t.
