Mick McCarthy believes Wolves winger Matt Jarvis has become a marked man since making his England debut.
Jarvis has been in outstanding form for the majority of the campaign and won his first England cap against Ghana at Wembley in March, but he has failed to sparkle in recent weeks and found defenders paying him more attention and was even substituted during last weekend's clash at Birmingham.
McCarthy said: "When Jarvo was just Jarvo who had done well for Gillingham, I said to him 'when you get in the England squad it's "he plays for England" and defenders harden their approach'."
He added: "He has beaten most of the full-backs in the Premier League this season and given them all a tough time.
"But, when you get that upgrade in your status, you have to upgrade yourself because people treat you differently."
McCarthy, whose side entertain West Brom in Sunday's crucial derby, added: "If I ever played against someone like that my first thought was always 'he's having it'.
"I'd be that more motivated because I was against an international and Jarvo is finding the same."