Scotland manager George Burley has warned players who pull out of friendlies they could be jeopardising their place in his team for the World Cup qualifying campaign.
Burley had seven withdrawals for his debut as national team coach against Croatia in March and suffered four yesterday ahead of Friday's international against the Czech Republic.
Alan Hutton, James McFadden and Rangers duo Steven Whittaker and Kevin Thomson have all pulled out through injury, with Motherwell's David Clarkson now added to the already depleted squad.
With only the trip to Prague and the visit of Northern Ireland in August to come before the qualifying campaign begins in Macedonia in September, Burley insists those who turn up for the friendlies will have more chance of forcing their way into his plans.
'This is a very important issue and it is something we've got to address,' he said. 'The players who are playing will naturally have a big impact on whether they stay in the side for the World Cup. It's something I've got to consider.
'For me, these games are very important in getting a blend in the team for Macedonia. By the time that comes around, it will have been nine months since the European Championship campaign ended.
'Whatever happened there was nine months ago - it's about what happens in September that is important. That is something you've got to address. It's just one of the frustrations of being an international manager.
'The players who are playing have more of an advantage of being in the team than the ones who are not. They are in pole position and, naturally, if they perform well they've got a very good chance of staying in the side.'
Key players, such as skipper Barry Ferguson, Lee McCulloch and David Weir, as well as reserve goalkeeper Allan McGregor, were absent from the original squad as Burley took into consideration Rangers' long, hard season.
Several Ibrox players also missed the 1-1 draw with Croatia and Burley added: 'It's only my second game, despite taking charge in January, and I still haven't got anywhere near to seeing the squad available play for me.
'So that's a worry. For me, this is an important game. The only way you are going to get the right preparation is to get some sort of consistency in the team, so that when you come into the World Cup you have a feeling for the whole squad.
'It's a struggle to get the players together for the very few friendlies we've got, to be honest, and that's why these games are so important.'
One Rangers player who remains in the squad is striker Kris Boyd, who revealed this weekend that he will consider his future over the summer after growing frustrated at a lack of regular football.
He scored the winner in Saturday's Scottish Cup final, having also played a key role in the capture of the CIS Insurance Cup, and Burley insists Boyd does not need to fear for his international career.
He said: 'I know his capabilities and he is certainly a player you want in your squad. I would keep an eye on the situation and, when I bring him into the squad, I'll have a look at him.
'You have players who sometimes don't start every week but you know they can be match-winners. Boyd is one of them.'