The 29-year-old played under Louis van Gaal during Netherlands’ World Cup campaign in the summer and reports have suggested that the centre-back, whose contract expires at the end of the season, could be reunited with the United boss at Old Trafford next month.
Fabian Delph’s contract also ends next summer and Lambert admits Villa could struggle to retain the midfielder, as well as Vlaar.
“This is a brilliant club regardless what football you’re playing. Those two lads have been fantastic for me the three years I’ve been here,” said Lambert.
“They’re in their last year and from experience when you get into the Bosman ruling you hold that card.
“I’m delighted with the way they’re playing. Whether they’re in their last year or have ten years to go those lads are right behind the football club at the minute."