Bent will be sidelined "for a few weeks" after suffering a hamstring injury during Villa's 4-1 midweek win at Norwich in the Capital One Cup.
Andreas Weimann came off the bench to effectively replace Bent with a two-goal blast at Carrow Road and is described by Lambert as "a natural finisher".
But Lambert knows the importance of players chipping in from all areas of the pitch as Villa look to improve on a tally of 12 goals in 16 Barclays Premier League matches at Liverpool.
Lambert confirmed: "Darren went for a scan and has got a problem with a hamstring that will keep him out for a few weeks.
Asked if the striker would miss the Christmas programme, Lambert said: "Yes, probably the way it is looking. Maybe four weeks.
"It's a blow for him. In football you just never know when it might happen on the pitch. I saw him do it but we have just to get it healed."
Weimann, Christian Benteke and Gabriel Agbonlahor have shouldered the responsibility for the majority of Villa's goal output, although Brett Holman has netted twice in the last three games.
But Lambert said: "You are looking for goals all over the pitch. It's not just about Christian, Andreas and Gabby.
"You have got to spread it out if you can. The way we are playing we are certainly creating chances, which is the pleasing thing. You just hope the lads will be confident enough to go and take them."