Spirits were high around Villa Park after back-to-back wins over Norwich City and Chelsea, but Villa were brought back down to earth with a bump against Midlands rivals Stoke.
Villa had led after five minutes through Christian Benteke before the visitors recovered in spectacular style to go in 3-1 up at half-time.
Peter Odemwingie levelled after 22 minutes before Andreas Weimann's slip let Erik Pieters in to square for Peter Crouch to convert. A mistake from Leandro Bacuna then allowed Marko Arnautovic to set up Steven N'Zonzi for Stoke's third three minutes before the interval.
Arnautovic created his side's fourth in the final minute, easily getting the better of Bacuna before cutting the ball back for Geoff Cameron to complete a miserable day for Lambert.
"We were second best, that wasn't good enough," he told Sky Sports.
"We had a really good start, scored a really good goal, but the goals we lost were really, really poor.
"But take nothing away from Stoke, they deserved to win the game.
"Maybe the Chelsea game took a lot more out of us than I thought but I don't want to make excuses, we were well beaten.
"You've got to keep learning the game and try to do as well as you can but you can't play like that and expect to win."
