Ousmane Dembele opened the scoring in the fifth minute and penalties from Antoine Griezmann and Philippe Coutinho guided Koeman's side to a comfortable victory and the manager explained his new system after the game.
"Messi's quality speaks for itself", said coach Ronald Koeman.
His comments came after his side earned an underwhelming 3-1 win over Gimnastic de Tarragona in a pre-season friendly on Saturday. De Jong was also able to play a full half in his preferred position as a controller.
"It's perhaps a little different and more defensive to what we have seen in the last few years", Koeman told the club's official television channel.
Two Los Angeles County deputies shot in ambush, officials said
Los Angeles County Sheriff Alex Villanueva speaks at a news conference in Los Angeles Thursday, Sept. 10, 2020. One of the agitators got into a struggle with deputies that were trying to arrest him for not cooperating.
Lionel Messi wore the captain's armband in his first match since he opted to abandon his plans to leave Barca, although Luis Suarez and Arturo Vidal were left out of the squad as the club is still trying to offload both players.
"I think this team can do it because we have midfielders to play like that".
Barcelona's next game is against Girona in a friendly clash on Wednesday before opening their season with a tie against Villareal next weekend.
Barca are sitting out the first two weekends of the new La Liga season which began on Saturday due to participating in the Champions League "Final Eight" tournament last month.
Demnark's Kragh Andersen scores first Tour de France win on stage 14
Guillaume Martin, third overall at the start, cracked in the penultimate climb and crossed the line 2:46 after Roglic. We are good friends but we both want to win. "We talk to each other and we're developing as a team".
Koeman is said to be keen on the Dutch duo of Gini Wijnaldum and Memphis Depay but no concrete offer has been made yet for the players.
"What we want to do right now is focus on our fitness and then over the next two weeks focus on more tactical questions".
'The most important thing is that fortunately there have been no injuries. We only have four weeks, not six.
New film Cuties, about dancing 11-year-olds, leads to #CancelNetflix campaign
Cuties is streaming on Netflix, so you can determine for yourself whether the film is tasteless or simply badly marketed. On the good days, you get paid to watch a Terrence Malick film... on the bad days you are forced to endure 'Cuties' .