Van der Vaart, who has become the club's new talisman since his summer move from Real Madrid, failed to train this morning and went for a scan on an ankle knock.
Fellow midfielder Bale, whose Champions League exploits this season have made him one of the most talked-about players on the planet, is suffering with a shoulder injury picked up in Saturday's north London derby.
Manager Harry Redknapp appeared more optimistic this afternoon about the latter's chances of being fit but admitted Van der Vaart was "struggling".
"Obviously, he'd be a big loss to us - he's been in great form," said Redknapp, before pointing out the Holland international's loss would be offset by the recent return of striker Jermain Defoe from injury.
"Jermain Defoe's coming back as well, so that's a big bonus for us. Whether I start him or bring him off the bench, he'll play a part in the game for sure."
Source: PA
Source: PA