If it can happen to Carlos Ancelotti and Chelsea it can surely happen to Roberto Di Matteo and Albion.

The Italian coach, who had taken his Baggies team top with an unbeaten start to the season, said: “We did not play a good game – it was a bad performance. I do not know why we did not play well.”

“But these things can happen after a lot of victories. We need to react well to this defeat and sometimes when you lose there is new motivation.’’

The best thing that could be said about the Baggies’ first defeat of the campaign is that at least they were in good company, as the Premier League leaders suffered precisely the same unexpected tumble in a game they were expected to stroll.

As Ancelotti’s words after Chelsea’s 3-1 defeat at Wigan suggest, everything now is about the reaction – his team in a Champions League match while Di Matteo’s travels to Barnsley for one of those fixtures which capture the spirit of the Championship.

Di Matteo’s captain Scott Carson said what all players say after a long period of success has come to an end – that the defeat will be a “blessing in disguise,” a wake-up call to remind the Baggies nothing is easy in the scramble to reach the Premier League.

But on this occasion, the goalkeeper’s words carried extra substance. Albion were complacent and sloppy and played too many minutes of this game expecting something to happen but not making it happen.

Possibly without knowing it, Carson himself was a prime culprit. Palace’s first attack broke down because of an offside call but the goalkeeper took an age retrieving the ball and setting himself for the free-kick.

In one tiny and early moment in the game, the goalkeeper summed up the Baggies’ display. There was no urgency or tempo and The Hawthorns, normally so boisterous, responded with a passable impression at times of the Emirates library.

All of this will stick in the craw more than usual for many Baggies supporters, because of the identity of the man who scripted Crystal Palace’s surprise conquest of their team.

Neil Warnock is about as popular with them as dog mess in a swimming pool, a spill-over from the infamous Battle of Bramall Lane when they will always feel the then Sheffield United manager stepped over the line of what is, and is not, acceptable on a football pitch.

His ham-fisted attempts to flatter his way back into their good books by saying nice things about the club subsequently will not fool them. But equally, they will acknowledge that he did a number on the Baggies in this game and it worked perfectly.

Of course, Palace defended deeply as Albion knew they would and they did so with Warnock’s trademark physical dimensions. Central defenders Paddy McCarthy and Jose Fonte, for example, spent the entire game winding up Roman Bednar to leave the big man boiling in frustration and distracted.

But the most damaging spanner in Albion’s works were tossed in by their pacy front pair Sean Scannell and Victor Moses, who worked with furious energy to disrupt the home team’s efforts to play controlled possession from the back.

Scannell and Moses unsettled Albion more than any other pairing this season and set the tone for a disconcerting afternoon for the Saturday morning leaders.

There was particular havoc down Albion’s right flank, where Gianni Zuiverloon was enduring such a torrid time defensively he was moved upfield for new man Gonzalo Jara to have a crack in the same role.

Sadly, he fared little better and as a result, there was an unease about Albion’s defending even if Palace were only able to fashion the one chance – but it was the chance that mattered.

It came in the 63rd minute and had the stamp of Warnock’s brutal simplicity about it – but it would be enough to win the game. The combination of Danny Butterfield’s free-kick to the back post and the towering presence of Alassane N’Diaye drew a moment’s vulnerability from Shelton Martis, which saw the ball drop loose for the Palace midfielder to prod beyond Carson.

That roused Albion but not sufficiently to retrieve the game although it could be argued that for all their unease they still produced two isolated moments of quality, which bore the stamp of their lofty position in the table and on another day might have been rewarded with goals.

Both moves came to a climax, with Zuiverloon reminding us that he is as exciting and potent going forward as he can be fragile in defence and both finished with crosses into the path of Luke Moore.

But it was not to be Moore’s day. From the first chance in the 22nd minute, he blazed his shot too high. The second opportunity five minutes before Palace’s goal saw him control Zuiverloon’s centre with a wonderful touch at full stretch which left him time to finish with a right-foot effort from 10 yards.

But goalkeeper Julian Speroni was the equal of him, springing from his line quickly to make a point-blank save –  a good moment for the Palace No 1 but one Moore will feel he should never have been able to enjoy.

The Baggies should not waste too much time beating themselves up over this setback, which prevented their equalling the club’s best League start of nine unbeaten games. As Di Matteo’s compatriot at his old club reminded him, it is the history Albion can make in the future that counts.

A week after the heights of their spectacular Middlesbrough mission, an old enemy returned to remind them that no team can drop off the pace in the Championship and expect to get away with it.

As long as they heed the lesson, it will have been one worth suffering.