Mainz GM Christian Heidel fears for Bundesliga clubs over the spending power of the Premier League.
Mainz lost Shinji Okazaki to Leicester City last month.
"You are getting clubs like Leicester who are now capable of buying Mainz's best player," Heidel told the Die Welt newspaper.
"Okazaki's turning 30 and he's only got one year left on his contract, yet they are still prepared to pay a double-figure million fee for him.
"This new situation is mostly going to affect the clubs from the middle and lower regions of the Bundesliga.
"England are our new rivals. The amounts they pay their players by the week are the same as what we pay by the month."