On the eve of Manchester City's game against Liverpool, Sneijder reminded Wirtz.
Sneijder said: "You can perform well in your own country, but you may encounter adaptation problems in other countries. This is the case with Dutch and German players, and I see the same situation with Wirtz now."
Liverpool signed Wirtz from Leverkusen this summer for about 125 million euros, but he has so far failed to achieve the expected performance. In 15 official games, Wirtz had only 3 assists and no goals.
Sneijder continued: "When you come to a club as a big-name star, you have to immediately show why they signed you. If you can't do that, they will lose interest in you very quickly. You have to show it immediately. Now you have to perform quickly, otherwise it's over."
"He is a superstar in Germany, but here he also has to prove that he can establish himself abroad. The key is to put him in the position where he is best suited."