Chelsea has been held to their third goalless draw in the space of a week after failing to break down 10-man Leicester City at Stamford Bridge on Saturday.
The Blues, whose winless run now stands at four matches in all competitions, grew into the match after a disappointing first-half showing but could not find a way through.
Leicester, beaten in 12 of their most recent 14 meetings with Chelsea in all competitions, saw their task become even tougher when Ben Chilwell was dismissed with a quarter of the game to play, but they held on for a share of the spoils on another day of frustration for Antonio Conte.
Wilfred Ndidi failed to make the most of the best of the openings, heading a bouncing ball goalwards a little too close to Thibaut Courtois, who still had plenty of work to keep it out.
Jamie Vardy also squandered two half-chances in quick succession, hooking one attempt into the side-netting and scuffing another wide of the target, while Shinji Okazaki missed the mark from six yards.
A fatigued Chelsea were very much second best in the first half, showing just two changes from their midweek draw with Arsenal here, though they did have openings of their own through Eden Hazard and Cesc Fabregas.
Mahrez showed glimpses of what he is capable of throughout the afternoon, but his performance was soured somewhat when taking a dive just short of the hour mark, with retrospective action possibly to follow.
Conte was cutting a frustrated figure on the sidelines, being forced to use the last two of his changes – having lost Gary Cahill to an early injury – by bringing on the fresh legs of Pedro and Willian.
Chelsea, boasting that impressive record against the Foxes – just one league loss here in 26 games – began to rack up the shots on target as former city ace N’Golo Kante and Willian both asked questions of Schmeichel.
Despite seeing far more of the ball in the closing stages, however, the champions ultimately struggled to create much and therefore missed out on the chance to climb into second place.