Villa's second away victory of the season - secured courtesy of Libor Kozak's first goal for the club - was soured by the sight of last season's top scorer limping away from the action midway through the first half.
Benteke slipped when looking to control a ball out of defence and appeared to stretch his groin. He attempted to play on but was forced off, to be replaced by Kozak.
"The medical staff reckon it's his hip flexor," he told BT Sport. "Hopefully it's not too bad.
"But Libor Kozak came on and scored within 90 seconds which shows he'll endear himself to the crowd."
Lambert also praised the effort of his team to record their first clean sheet in 27 Premier League matches.
"We came here with a lot of injuries so credit to every one of them," added the Villa boss. "They were outstanding.
"I'm delighted with the way the lads have performed."