Jack Butland's own-goal cancelled out Xherdan Shaqiri's classy opener as Stoke City and Leicester City played to a 1-1 draw in the Premier League on Saturday.
Leicester had Stoke on the ropes with a bright start which yielded three corners in the first two minutes, but that early momentum soon dissipated as the visitors settled.
However, Butland gifted Leicester an equaliser with an own goal midway through the second half when he misjudged a Marc Albrighton cross.
Shaqiri burst through the middle and his deflected pass fell to Eric Maxim Choupo-Moting, who turned inside Mahrez before curling a low shot that Kasper Schmeichel saved diving to his left in the 13th minute.
The England global diverted in Marc Albrighton's cross into his net to deny Stoke City their first win from their last four games.
It was a blow for Leicester so close to the break but the hosts responded well at the beginning of the second half, putting Stoke under pressure once more.
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Lambert has been lauded by the players at the Potters, as he demanded that no phones are used while the players eat at the training ground, as he looks to boost squad morale, but it's on the pitch where he will prove his worth, and today's display showed he could keep them in the division.
The keeper mishit his clearance to Joe Allen who quickly prodded the ball to Shaqiri, the Swiss worldwide subsequently hit an effort from 40 yards out but it bounced just wide of the open goal.
'We had already been playing for about 70 minutes [though]. Albrighton's corner on the right broke to Mahrez inside the box, who curled a powerful effort which flew through a number of bodies and looked destined to end up in the net until Butland somehow clawed it away.
Then Mahrez seemed certain to claim a late victor when a defensive error left him through on goal but Kurt Zouma and Butland denied him.
Lambert was referring to a strong one-handed stop to deny Riyad Mahrez as Butland began to go some way towards making amends for his mistake eight minutes previously.
"Not enough to win today", the Frenchman told BBC Sport.