Madrid - Once again, the Spanish football league has been laid low by the "FIFA Virus."

This is the name given by the Spanish media to the injuries and fatigue suffered by top players through playing World Cup qualifiers or friendlies for their national teams.

Catalan sports paper Mundo Deportivo estimated on Friday that around 20 per cent of international players return from national team duty with some kind of injury.

"The 'FIFA Virus' has struck again," bemoaned Radio Marca on Friday, before reading off a list of players who returned to their Spanish clubs on Thursday in poor shape, as a consequence of this week's international matches.

Top of the list is Betis midfielder Mark Gonzalez, who will be out of action for around three weeks with a severe spraining of the ligaments in his right knee, suffered in Chile's 1-0 win over Argentina.

Gonzalez - who has been plagued by knee injuries throughout his career - may need another operation, which would keep him out for even longer.

This is just what Betis - bottom of La Liga with just two points from six games - need.

The only crumb of comfort for troubled Betis is that crosstown rivals Sevilla have been even worst hit by the "virus".

No less than four Sevilla playesr have returned from national team duty injured: Frederic Kanoute, Ernesto Chevanton, Ivica Dragutinovic and Diego Capel.

In addition, Arouna Kone will be out for around six months after suffering a serious knee injury playiong for the Ivory Coast in September.

Sevilla president Jose Maria del Nido said on Thursday that "we clubs can only give our opinions...We try to make them (FIFA and the national federations) see the damaging sporting and economic consequences, but there is little we can do."

There is practically no Liga club that has not been hit by the "FIFA Virus" this week.

At Barcelona, Eidur Gudjohnsen will be out for around three weeks after tearing a muscle in the Iceland-Macedonia clash. The timing of the injury is ironic, because Gudjohnsen has finally started to look important at the Camp Nou, after two seasons on the bench.

Barca winger Pedo Dominguez is also out for around three weeks, after being injured playing for the Spain Under-21 side.

Even worse for Barca, Lionel Messi has returned from the Chile-Argentina clash battered and bruised, and will probably sit out Sunday's game in Bilbao.

Argentina's other starlet, Sergio Aguero, is in even worse shape after the defeat in Santiago, and will probably miss Saturday's Madrid derby between his club Atletico and Real.

Not that the champions Real have managed to avoid the "virus".

Mahamadou Diarra will miss "El Derby" after picking up an injury playing for Mali, and Miguel Torres is out for around a month after tearing a muscle in the Spain-Switzerland Under-21 clash.