Norwich City knew it already but this was a painful reminder the Canaries will be punished if they drop their guard in the Premier League.

The hosts' spirited response after Jeff Schlupp added to Jamie Vardy's penalty was commendable but Alex Neil and his under-performing players will know there was a gulf between these two clubs for an hour at Carrow Road.

Nor should contentious penalty episodes cloud the feeling Leicester were too slick, too streetwise, too cohesive during that period to nullify a lacklustre Norwich.

Vardy's cunning convinced Mark Clattenburg to award a spot kick after the England international had eased himself the wrong side of Seb Bassong. Similar justice was not forthcoming when Robert Huth pinned Cameron Jerome in a heavyweight aerial duel and appeared to handle Dieumerci Mbokani's header.

The Dynamo Kiev frontman pressed his claims for inclusion after the international break with a potent cameo. Kasper Schmeichel tipped a header superbly onto his bar but was left stranded with a clever flick guided inside the far post.

Norwich surged forward in the aftermath with Kyle Lafferty adding extra ballast and Nathan Redmond's goalbound shot could have salvaged a point in the midst of one final push when it brushed Danny Drinkwater's back and spiralled wide.

But it was the Canaries' spirit and collective determination that upset the Foxes' serene progress towards a routine win. Neil wants more than heart, he wants head and the performance of his frontline options was the greatest cause for concern.

After the high of West Ham tinged by the stinging low of a late equaliser at Upton Park, the curve plunged again here in those opening 60 minutes.

Neil and his squad simply cannot afford such peaks and troughs and expect to maintain solid Premier League progress. Leicester were dominant in every facet. Vardy and Shinji Okazaki pressed and harassed to deny time and space to construct from deep. Drinkwater and N'Golo Kante suffocated Wes Hoolahan, who was a peripheral figure until Norwich adopted a more direct approach after Schlupp's counter.

The hosts' turned over possession cheaply and when they had the ball were too laboured in their movement. Leicester shuffled leisurely back into a defensive shape and exploited the energy and urgency of Vardy.

The prolific frontman may not have endeared himself to the majority inside a record all-seater attendance at Carrow Road; particularly with his recovery from what appeared a serious knee injury suffered in a jarring fall, but Vardy's industry and work ethic subjected Bassong and to a lesser extent Russell Martin to an uncomfortable shift evoking memories of Southampton.

That chastening defeat at St Mary's had hitherto proved an anomaly in Norwich's timeline. Leicester is now another, albeit the Canaries' roused themselves in the pursuit of parity in a way they were unable to achieve on the south-coast, given their numerical disadvantage through Steven Whittaker's red card.

Both outings were notable for a worrying sense of drift in thought and deed. Norwich have looked assured, for the most part, back in the Premier League but Leicester exposed lingering vulnerability.

Such was the Canaries' fine form going into this contest, Claudio Ranieri paid them the compliment of changing his line up to thwart Norwich's prowess down either flank. Riyad Mahrez, arguably alongside Vardy the stand-out performer so far in the country, was benched to nullify a perceived strength.

The Canaries are seemingly no longer under the radar, which brings with it different pressures and expectations. They are better than they served up for an hour at Carrow Road and Neil, his players and fans know as much.

Norwich were forced to stew on that Southampton mauling for the duration of the last international break. To their credit the response was emphatic, with a commanding league win over Bournemouth and those merited points at Liverpool and West Ham. There was also progress in the League Cup against West Brom for good measure.

Do not bet against another stirring reply the other side of this latest international shutdown.

Neil has already shown he is both a pragmatist and a realist in team selection and outlook. He was acutely aware too many had fallen below their own personal standards against Leicester. Some may now pay the price.