In suffocating August heat at the start of the season Real Madrid stayed ice cool to crush Barcelona 5-1 on aggregate in the Spanish Super Cup.
It was a show of force from Spain's dominant side, the double winners exerting their power over Barcelona and leaving their arch-rivals on the verge of crisis.
New Barca coach Ernesto Valverde looked on helplessly as Brazilian forward Neymar joined Paris St Germain and Real looked unstoppable.
"It's the first time we've felt Madrid are superior," Barca defender Gerard Pique said after the game.
But as the months passed, it became clear that Real were not capable of defending their league title as Barcelona surged clear at the top of the standings.
Madrid's league hopes lay in tatters by December, the Catalans raiding the Santiago Bernabeu with a 3-0 win in the Christmas Clasico and moving 14 points of Zinedine Zidane's team.
Real were dumped out of the King's Cup in January on away goals by unheralded Leganes and Barcelona went on to win that trophy for the fourth season in a row.
That was the first step towards a near-certain double for Barcelona, who need one point in their remaining five games to wrest the title back from Real.
Real will ease the pain by retaining their Champions League title, their only hope of salvaging a disappointing season.
They face Bayern Munich in the semi-finals as they bid to win it for a third season running, having last season become the first side to retain the trophy by beating Juventus in the final.
The German champions, however, are desperate for revenge after they were eliminated 6-3 on aggregate at the quarter-final stage by Zidane's side last season in controversial circumstances.
"You need a better referee for a quarter-final," complained then Bayern coach Carlo Ancelotti after his team had two men sent off over the two legs and Real scored goals from offside positions.
"We're working hard and, if we've done it twice, why wouldn't we go for that third consecutive Champions League?," Real defender Dani Carvajal said ahead of Wednesday's first leg in Munich.
It would not be the first time Real's season has been salvaged by a European triumph.
In 2016 they lifted the trophy after Barcelona won the double and in 1998 they triumphed after finishing fifth in La Liga.