Manchester United's slump has jeopardized some players' chances of making England's World Cup roster, coach Roy Hodgson has warned.
United won the Premier League by 11 points before Alex Ferguson as manager retired last year but is 18-12-6 with two games left, in seventh place.
Hodgson wants to take confident players to Brazil rather than those who have been underperforming with their clubs.
"They're one of the few teams that have had a lot of English players, but football players have to accept unfortunately their England careers are tied up with their club careers," Hodgson said. "If it's not going well in their clubs, and it's not going well for them in their clubs, and other players are doing extremely well in their clubs, it does put your position as a national team player under some sort of threat.
"I'm pretty certain that the Man United players will understand that, that there's no God-given right that because they've played in a few games up to now, they'll play all the games in the future."
While Wayne Rooney can be certain of a roster spot if he is fit, the striker's United teammates could face an anxious wait before Hodgson announces his 23-man squad on May 12. Among United's England contingent are defenders Phil Jones and Chris Smalling, midfielders Michael Carrick and Tom Cleverley, winger Ashley Young, and forward Danny Welbeck.
"It's up to me to pick who the best players for the job are at any given moment," Hodgson said. "Now that doesn't mean to say you'll choose a player for the national team every time he scores a goal, but it does mean you are judging over a relatively short period of time."
England plays its World Cup opener against Italy in Manaus on June 14 following a week-long trip to Miami to play exhibitions against Ecuador and Honduras.
"I don't think it's our job to keep them occupied," Hodgson said. "Once you sign up for (the World Cup), you shouldn't then be saying, 'Oh, I'm missing my family. Oh, I'm bored. Or what can you do to help me?' because there's nothing we can do to help you.
"It's like a soldier saying, 'I'll sign up for the army, but I don't want to see any action. I'm a bit bored here sitting around these barracks, every day with nothing to do,'" Hodgson added. "They must have plenty of boredom in their lives."