Leicester City denied Frank Lampard a first win as Chelsea manager as the Foxes earned a 1-1 draw at Stamford Bridge on Sunday.
U.S. winger Christian Pulisic went to ground near the end of the first half after awkwardly blocking a cross, but despite looking like he might have picked up an injury he was able to carry on as Chelsea took a 1-0 lead into the dressing room.
Ndidi made amends for his first-half blunder in the 66th minute, rising up to head James Maddison's cross past Kepa Arrizabalaga to give Leicester a deserved equaliser after the visitors had dominated proceedings in the second half.
Before the match, fans in the Shed End unveiled a banner emblazoned with the huge words: "Welcome home, Super Frank" and Lampard told reporters later that it was "the stuff of dreams" to return to Stamford Bridge.
But his focus was on how Chelsea failed to maintain their early momentum against Leicester and allowed the visitors to run much of the game, something he said could only be partly blamed on his side's tiring midweek trip to Istanbul where they lost the Super Cup final to Liverpool after extra time and penalties.
"That was the disappointing thing for me - that we couldn't sustain the period of the early part of the game," Lampard said.
"I don't expect that 100-miles-an-hour energy for the 90 minutes, but I do expect that when you rest, you can keep possession of the ball better. That was the big thing for me today."
Lampard said he took more comfort from the 4-0 defeat to Manchester United last weekend, when Chelsea played well for long periods, than he did from Sunday's draw.
"We can do better than we did today," he said.
In the opening minutes, Mount linked up impressively with striker Olivier Giroud, and U.S. winger Pulisic, another new face at Chelsea, also went close.
Leicester coach Brendan Rodgers lamented the missed chances after his side took control of the contest.
"I think we should have won it, to be honest," he said. "Second half, I thought we were very, very good."
The result gives Chelsea their first point of the season, but leaves former club legend Lampard in search of a first win since taking over as manager.