The Villa boss is preparing his squad to face the Potters at Villa Park this weekend, but defender Vlaar is still struggling with a calf problem which ruled him out of the last two games with Reading and QPR.
Winger Charles N'Zogbia has returned to training after a six-week absence with a knee problem but Lambert is still to decide whether he will be involved in the squad.
Left-backs Stevens and Joe Bennett are still sidelined with respective ankle and knee problems as Villa look to extend their unbeaten run to four matches.
"It's the same squad that more or less travelled down to QPR," said Lambert on the club's website. "Charles is back training. Ron is still a doubt and I'm not too hopeful he will be fit.
"N'Zogbia trained yesterday for the first time since he's been out."