Bayern Munich is experienced, and if we compare the scores of these two teams, Bayern Munich will undoubtedly be ahead. Galatasaray's squad is not very strong. But their main strength is the excellent understanding between the players. And that's why they were able to beat Manchester United.
They were also able to win Manchester United because their defense has been very bad this season and maybe we expected too much of Manchester United when they played against Galatasaray. Bayern are a bigger team and a team in a much better position than Manchester United, so winning Galatasaray should not be a challenge to them. Newcastle who have done well already in their tough group will play another tough game against Borussia Dortmund, but they should be able to win that game too because Dortmund is not as strong as they used to be this season.