For Barcelona, this was their fourth game at the Nou Camp since it reopened last month after redevelopment work.
The club last played a Champions League match there in October 2022 when they lost 3-0 to Bayern Munich, although they did then play in the Europa League in February 2023.
Work began on the Nou Camp in June 2023 at a cost of about £1.1bn, with the goal of modernising the stadium and expanding its capacity to 105,000 – making it one of the largest grounds in the world.
After they spent the past two seasons playing largely at the Estadi Olimpic, which hosted the 1992 Olympics, the Nou Camp reopened with a reduced capacity of 45,401, with work still to be completed on the top tier and the roof.
And Flick’s side have now won all four of their matches back at their traditional home.
Frankfurt have struggled domestically and were beaten 6-0 by RB Leipzig on Saturday, but opened the scoring and had chances to double their lead, only for Ellyes Skhiri and Fares Chaibi to shoot over.
However, two goals from Kounde in a four-minute spell transformed the match for a Barcelona side that had lost 3-0 at Chelsea in their previous Champions League tie.
The only negative for Barcelona was a second-half booking for Yamal following a foul on Brown and that means the teenage forward will be suspended for the trip to Prague.
