Lambert revealed Delph missed the West Ham clash with a sickness bug, similar to the one which kept Ciaran Clark out of the Tottenham clash.
He told Villa's website: "When you look at the ones we lost against West Ham, Fabian has been fantastic for us.
"He had a bug on Thursday and Friday so that was a blow to see him miss this game at Upton Park. 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 all right for the next game.
"He's been playing great for us."
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