The 18-year-old Fulham player was loaned to Cardiff last week and he has admitted that he was instantly impressed by the quality of his new teammates.
Frei said: "Straight away I can see what a good side Cardiff are. You only have to look at some of the players here.
"Cardiff are top of the league now and they definitely have the quality to go up and when they do, in my opinion, they will stay there."
Frei has scored one goal in 25 games for Fulham.