Lewandowski took part in the pre-game warm-up session with his teammates, this means that he might make his debut in El Clasico next week against Real Madrid.
Barcelona have signed Poland striker Robert Lewandowski from Bayern Munich on a four-year contract worth 50m euros (£42.6m).
The 33-year-old had one year left on his contract with the German champions but in May said: “My story with Bayern is over.”.
He has joined his new team-mates in Miami as part of Barcelona’s four-match tour of the United States.
“I’m finally here. I’m delighted to be at Barca,” Lewandowski said.
“The last few days have been very long, but the deal is done and now I can focus on a new chapter and challenge in my life. “I’ve always wanted to play in La Liga and for the big clubs.
“I’m here to help Barca get back to the top and win as many titles as possible.”
Lewandowski, who has a buyout clause of 500m euros (£425.9m), joined Bayern on a free transfer in 2014 after his departure from Borussia Dortmund.
‘Lewandowski’ knew he wasn’t going to featuring in the game, but he took a very keen interest in everything that happened on the field.