Perth Glory coach David Mitchell has conceded the difficulty of juggling his players' World Cup ambitions with his club's aim to reach the A-League finals.Glory players Chris Coyne, Jacob Burns and Mile Sterjovski are trying to secure stints at overseas clubs during the January transfer window in order to keep alive their hopes of earning a spot in Australia's World Cup squad.Socceroos coach Pim Verbeek has made it clear A-League stars not playing regularly after the domestic season won't be considered for South Africa.That means some players could leave their A-League clubs before the finals.Coyne was in China last week speaking with Super League club Shandong Luneng, and Mitchell conceded the defender's travels affected his performance for the Glory.Coyne endured a wretched game in Perth's 6-2 defeat to Melbourne Victory at Etihad Stadium on Saturday night, with several defensive blunders and a booking, and Mitchell substituted him before half-time."With Chris going away it probably affected him in this game, it was there for all to see," Mitchell said."It's a situation where we knew about that and it's not easy to coach or manage or whatever, and there's nothing come through for the players yet, so that's in the air."We've just got to deal with that when it happens."But Burns said the players had little choice than to pursue overseas stints if they were to remain eligible for national selection."We've been told by the national coach that that's what it's going to take to be involved in a World Cup. End of story," the Perth skipper said.Burns said he had not received any strong offers from overseas clubs, and until he did would remain focused on the Glory."It's every kid's dream, which I've said about 15 times, to be involved in a World Cup," he said."If you've got the head coach saying you can't be on the beach when the season comes to an end, you've got to be playing regular football, there's no question ... if it happens, it happens."The club knows, but I'm not thinking about it."First and foremost my job here is at Perth to get us into the finals and it will be the job until otherwise."Perth's terrible showing against Melbourne left them among a ruck of teams vying for sixth spot.The defeat continued poor form on the road, and they must rebound quickly to play Adelaide United at Hindmarsh Stadium on Tuesday night."In a perverse sort of way it might be a blessing in disguise for us to wake up and say 'Right, OK, we're not a foregone conclusion to make this top six'," Mitchell said."It's still in our hands, but we've got to smarten up and take responsibility."