The visitors went into the game knowing that a win would take them three points clear at the top of the LaLiga table and they duly did their bit as they cut their opponents to ribbons in the opening 45.
Messi got the ball rolling with 17 minutes gone as he curled a stunning free-kick into the top right corner of Diego Lopez's net after being felled by Oscar Duarte and the 'Blaugrana' didn't look back from the, with each and every one of their goals fit to take the breath away.
Just nine minutes after Messi's opener it was two, the Argentine again playing a vital role as he found Ousmane Dembele out on the left with a wonderful pass, the Frenchman cutting inside onto his right foot and lashing a fierce curling effort into the far corner.
The visitors were in complete control and could have been out of sight shortly afterwards as both Luis Suarez and Messi rattled the woodwork, but the Uruguayan did eventually add his name to the scoresheet on the stroke of the break to all but put the game to bed.
Dembele turned provider this time, slipping his fellow forward in in the left-hand channel, with Suarez doing brilliantly to hold off the challenge of a defender and somehow squeeze a finish through the legs of Lopez and into the far corner from the narrowest of angles.
Understandably, Barca took their foot off the gas in the second half, though the feeling that they could re-find their intensity and cutting edge at a moment's notice remained.
Lopez did well to deny Messi with his legs after a rapid counter, but there was nothing the stopper could do with 65 minutes gone as the diminutive genius curled him his second sumptuous free-kick of the night, this time finding the opposite corner with a set-piece that appeared to favour a right-footer.
Substitute Philippe Coutinho was denied the icing on top of the cake by Lopez's strong left hand shortly after coming on, before one incident pretty much summed up Espanyol's night.
Duarte thought he had netted a consolation for his side as he prodded home Sergio Garcia's free-kick at the far post, only for the goal to be disallowed after a lengthy VAR review.
The hosts deserved credit for the way they continued to go in search of a goal, but they were ultimately outclassed all over the pitch.
The win sees Barcelona go three points clear at the top of the LaLiga table, whilst Espanyol drop to ninth.
December 8, 2018