Ayoub El Kaabi scored twice while Ismail El Haddad and Achraf Bencharki also found the net as rampant Morocco broke Mauritania's bold resolve to begin their African Nations Championship campaign with a convincing 4-0 win on home soil.
Despite their overwhelming dominance, the hosts had been frustrated by Mauritania and a series of heroic stops by goalkeeper Souleymane Brahim before El Kaabi, reacting quickest to Ismail Haddad's delicious through ball, finished calmly to break the deadlock in the 66th minute.
Undoing much of his earlier good work, Souleymane was culpable for Morocco's second, appearing to get both hands to a weak effort from El Haddad, only for the ball to ripple into the roof of the net in the 72nd minute.
El Kaabi added Morocco's third - a scoreline that didn't flatter the hosts - with a right-footed shot from close range in the 80th minute, as one of the tournament favourites flexed their offensive muscles in front of their own fans at the Stade Mohammed V in Casablanca.
Substitute Achraf Becharki, capitalising on a Mauritania defence that had long since given up, added a fourth in stoppage time when he duped Souleymane and finished from a tight angle.
Morocco's offensive superiority was clear from the off, as the hosts sought to stretch and torment their opponents.
Immediately, it was clear that a key element of their gameplan was to exploit the pace of El Kaabi - playing on the shoulder of the last defender, and Souleymane had to be alert to smother the ball in the seventh minute.
That was just one of several nervous moments for the visitors during the early stages, with Sidi Mohamed Bilal's last-gasp clearance denying the Atlas Lions an early opener that might have set the tone for an even greater thrashing.
Jamal Sellami's side had further chances to take the lead during the first-half - with Mohammed Nahiri slamming a free kick over and El Kaabi sending a low shot wide - but it was Mauritania who had the only shot on target, a tame long-range effort from Lemrabott El Hacen.
Having enjoyed 67 percent of the possession during the first period, Morocco continued in the same vein after the break and Salaheddine Saidi was denied a 48th-minute opener when Souleymane tipped his looping effort over.
As the hour mark approached, and the partisan crowd grew less patient with their local stars, Morocco began to rediscover the zip and fluidity of the opening 10 minutes, although El Kaabi slipped with the goal apparently at his mercy after being picked out by Zakaria Hadraf's cutback.
The best chance fell to Saidi, but opting for power this time, he could still only watch on as Souleymane sprawled out to block his effort.
Moments later, the goalkeeper had no answer as El Kaabi, reacting quickest to beat the visitors' offside trap, finished cooly after being put through one on one.
Almost before Mauritania could settle and go in search of an equaliser, Morocco had added a second.
El Haddad, found by a delightful El Hafidi ball, cut onto his left and got off a snapshot, and while Souleymane dived low and appeared to get both hands to it, was unable to prevent the effort from crossing the line.
Even before El Kaabi added his second and Morocco's third in the 80th minute, Souleymane and his teammates had the look of defeated men, and substitute Bencharki added a delicious fourth - beating the beleaguered stopper with the outside of his boot from close range -- in the 92nd minute to wrap up a one-sided display.