The 23-year-old missed Saturday's goalless draw with West Ham due to a stomach complaint similar to the one that kept Ciaran Clark out against Tottenham a fortnight earlier.
However, Delph is likely to be available for the visit of Cardiff as Villa seek a first league win in five matches.
"When you look at the ones we lost against West Ham, Fabian has been fantastic for us," Lambert told reporters.
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"I'm pretty sure Fabian's bug is only a short-term kind of thing. He pulled out of training on Thursday. He came in on Friday but he still didn't look the greatest so we sent him home.
"There's been a bug going around. Ciaran had it the other week so hopefully Fabian will be alright for the next game."
Forward Andreas Weimann could face a longer spell on the sidelines after being forced off against West Ham.
"It looks like a hamstring at the minute. I don't know how severe it is," added Lambert.
"The thing is we've got one more game then we get a break so hopefully the break helps him."