Just 15 minutes into the end of the game, Lionel Messi came in for Inigo Ruiz de Galarreta, but the highlight of the events was the fans of the Argentine bursting into tears after getting an autograph from him.
Ousmane Dembele and Luis Suarez had Barcelona 2-0 up at the break before Andre Gomes made it 3-0.
"It is a pleasure to be in South Africa and I believe this huge crowd thoroughly enjoyed what both sides produced. When they scored the first goal in the first minute, we started to ask: 'How many goals were coming?'" he said. "The speed of the team was very high", he said.
"I am so happy with my boys because they always tried to play football the way I want them to - building from the back".
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That feat was last achieved in 1932 by Real Madrid, the arch-rivals of Barca, when the season comprised 18 fixtures compared with 38 now.
Luis Suarez doubled their lead with a well-taken finish through the legs of Denis Onyango.
Earlier, Percy Tau had missed a great opportunity to beat Ter Stegen in Barca goal while Denis Suarez headed against the post off Dembele cross.
Substitute Andre Gomes scored Barcelona's third in the 66th minute, before Messi was introduced to a rousing reception by the South African supporters in the 70th minute.
The Brazilians managed a consolation strike from Sibusiso Vilakazi in the 76th minute.