Fabio Capello has highlighted the importance of his squad playing regular first-team football ahead of next season's World Cup qualifiers.
Capello has been in Austria to keep an eye on Croatia at Euro 2008, the country that denied England qualification and are also their opponents in September.
"It's very important to see the players every week," Capello said.
"It's better for us if they play regularly because players are fit if they play every game."
Jermain Defoe is an example Capello can point to, with the striker moving to Portsmouth and forcing his way into the England squad before ending the season with two goals in two games for his country.
"Always when you are playing for the national team, it is not easy in your first game," Capello said.
"He will be with us for the next games as long as he is fit. I don't understand the criticism of (Dean) Ashton because the England shirt brings a lot of pressure. He is a good player."
Capello was at Ernst Happel Stadium to watch Croatia stutter towards victory over co-hosts Austria, but despite their performance he believes England face a huge test against Bilic's men.
"I need to know everything, all the secrets of this team - the system, the set-pieces and the movement when they have the ball," Capello said.
"It was an interesting game, Croatia played with a great unity and it is a very strong team because it is a group. They pressed a lot and defended very well.
"We have to beat Croatia. They are a good team with good organisation and they are a strong group. In the last half an hour against Austria their spirit was very important.
"It will not be an easy game, but we have to win against Croatia."