The banner before the match said it all. "God save the King!" read an enormous tifo unfurled by Barcelona fans ahead of their Champions League last-16 second leg clash against Chelsea. And as the game started, the King duly delivered.
Messi had pulled out of Barca's trip to Malaga in La Liga on Saturday to be present at the birth of his third son, Ciro, but he was back in the starting line-up for this all-important fixture and the supporters were clearly pleased to see him.
Ahead of these two teams' first meeting at Stamford Bridge in February, much of the talk had centred around Messi and how he had never scored against Chelsea. A late leveller to cancel out Willian's strike put paid to that, however, and the Argentine was clearly in the mood for more here.
Barca have been the best team in Spain over the past few years, yet the Blaugrana have seen their fierce rivals Real Madrid dominate in Europe by winning three of the last four Champions League titles.
Los Blancos were already through to the quarter-finals of the competition after making light work of Paris Saint-Germain and on Wednesday night, Messi made sure Barca will also be in the hat for Friday's draw.
It took him just over two minutes to influence proceedings as he found space on the right and drilled a low shot through the legs of Chelsea goalkeeper Thibaut Courtois to make it 1-0 on the night and 2-1 on aggregate.
And later in a first half in which Chelsea caused Barca quite a few problems, the Argentine embarked on one of those remarkable runs of his, taking on three players and dragging defenders in his direction before squaring for Ousmane Dembele to blast home his first goal for the Catalan club.
Messi's first two touches in the opposition area had been a goal and an assist. It was as devastating as it was brilliant and although Marcos Alonso hit the post with a free-kick in first half stoppage time, the Blues looked shell-shocked.
Chelsea started the second period positively and Barca boss Ernesto Valverde was an animated figure as he barked instructions to his players, with Alonso again a threat for the visitors.
But he need not have worried. Because Messi, who was being watched by Argentina coach Jorge Sampaoli, raced into the area after 63 minutes and again found the gap between Courtois' legs, this time with a powerful left-footed drive, to score his 100th Champions League goal.
It was also his sixth in this season's competition after something of a slow start in the group stages. Here he was, back at his breathtaking best when it mattered most to destroy a team renowned for their defensive discipline.
"It is what we always say: he is a player who makes the difference," Andres Iniesta said afterwards to beIn Sports with typical understatement. "It is a blessing that he is with us."
Indeed it is. After a short absence at the weekend, the King has returned for Barcelona – and he has his eyes firmly fixed on another Champions League crown this season.