Aston Villa angry with Switzerland's handling of injured Philippe Senderos

Boss Paul Lambert has warned Aston Villa may spell out how to handle their international stars in the wake of Philippe Senderos' injury.

The frustrated manager has been left with just two fit centre-backs ahead of Monday's visit of Southampton.

Senderos -- who had just recovered from a thigh problem -- returned to Villa from Switzerland duty after suffering a calf injury in training and is now sidelined for up to a month.

Jores Okore and Ciaran Clark are Villa's only fit recognised centre-backs and Lambert admitted the club will be extra vigilant, especially with Switzerland.

"We need to make people aware of things -- if that's what's going to happen to your player," said Lambert, who felt the Swiss had mismanaged his star.

"I think we will need to give [Switzerland] information now. If you bring players in, you need to do your homework.

"We've had discussions as a club and are not happy. The medical people aren't happy either.

"They'd known he was injured. They should have done their homework. They don't need us to tell them what he had done and what he needed to do.

"I think they should have known he had not played for a month before and only played six minutes against West Ham. Common knowledge tells you -- you have to know -- what guys have not done as much as other guys.

"We had a meeting with [CEO] Tom Fox and said we are not happy with the way things have been handled. This is not normal."

Skipper Ron Vlaar is also sidelined with his own calf problem he suffered on duty with Holland while Nathan Baker is out until 2015 after picking up a knee injury at West Ham.

Okore -- who is yet to play this season after recovering from a cruciate knee ligament injury -- stands by with Clark to face the in-form Saints.

"We're down to a couple of centre-halves," said Lambert.

"Nathan will be at least a couple of months. He's just done his knee, it's the back of his knee which is damaged but it will only need a rest."