Croatia boss Slaven Bilic fears the crisis at Tottenham could undermine his country's bid to qualify for the 2010 World Cup.
Luka Modric is Bilic's key player but the £16.5m signing from Dinamo Zagreb has so far struggled to make an impact at White Hart Lane.
Bilic, whose qualification hopes were hit by last month's defeat to England, also has Vedran Corluka in the Spurs squad, with Juande Ramos' men bottom of the Barclays Premier League and enduring their worst start to a season since 1912.
"I am worried about the results at Tottenham, where some of our key players are playing - defender Vedran Corluka and in particular Luka Modric," Bilic said on fifa.com.
"Luka is aware the situation is not good. He is aware that more is expected of him and that he has to lead the others.
"One of the things we must do at team headquarters is help set him on the right road."
Modric has been hampered by a knee injury in recent weeks and admits he needs to improve at his new club. "I am not satisfied with my performances at Tottenham. I have to do better and I can do better," said Modric.
"The problem has been a knee problem - it's been causing me pain."