The home side took confidence from their late chance in the first period as they made a positive start from the kick-off, showing a clear desire to challenge Leicester's largely untested defence from the off.
"He has good attributes to play in the Premier League with his pace, his good engine and penetration". Only half an hour had been played but it seemed the cup tie was already over for Peterborough, although they did improve in the final stages of the first half.
In a passionate rant on Soccer Saturday Merson fumed: "I think it's disgraceful".
Chelsea face Newcastle in another all-Premier League clash on Sunday when league leaders Manchester City continue their bid for an unprecedented "quadruple" of major trophies (Premier League, FA Cup, League Cup and Champions League) away to second-tier Cardiff.
"If I was a Leicester fan... it's a joke, an absolute joke".
In came Danny Simpson and Christian Fuchs, who were both vital players during Leicester's Premier Leageu title-winning campaign, Euro 2016 victor Adrien Silva and three-time Europa League champion Vincente Iborra.
But, in a shock turn of events, in turns out Puel knows more about football management than Merson. No other player has more in the competition.
The Foxes are unbeaten in their last five games and are yet to concede a single goal this year, a run they'll look to maintain as they travel to the ABAX Stadium.
The hosts got a goal courtesy of poor defending from Andrew Hughes in the 58th minute.