Burnley wasted little time in ending Peterborough's hopes of a giant killing in the FA Cup as they returned to winning ways after three successive Premier League defeats.
Clarets boss Sean Dyche rotated his squad and made eight changes following the defeat to Aston Villa on New Year's Day, with former England No 1 Joe Hart one of the players recalled for only his second start of the season.
But the Clarets still came flying out of the blocks with goals from Jay Rodriguez, Eric Pieters and Jeff Hendrick in the first 24 minutes putting them in command of the third round tie against Darren Ferguson's League One play-off chasers in front of only 8,043 at Turf Moor.
Rodriguez tapped in the first in the eighth minute after Chris Wood's header had been parried by Christy Pym, with Peterborugh players appealing in vain for offside.
Pym then saved Joey Gudmundsson's shot from making it 2-0 but Peterborough's relief was short-lived because Eric Pieters fired in his first goal for Burnley from 25 yards after chesting down Rhys Bennett's hasty clearance in the 15th minute.
A flowing Burnley move, started by James Tarkowski's long pass out to Aaron Lennon, ended with Jeff Hendrick adding the third after 24 minutes.Matt Lowton cut the ball back for Jeff Hendrick whose shot from the edge of the area took a deflection off Posh skipper Mark Beevers.
To their credit, the Posh shrugged off the shock of Burnley's early barrage to have some threatening moments themselves.
Debutant Reece Brown - signed on loan from Huddersfield 24 hours earlier - shot just wide of the far post, Marcus Maddison had a shot from a tight angle saved by Hart while top scorer Ivan Toney slid a close range chance wide when he should have scored.
Toney made amends by pulling one back thanks to a mistake by Matt Lowton. The Burnley right back miscued his attempted header back to Hart allowing Toney to race past the stranded goalkeeper and steer his shot into an empty net for his 17th goal of the season.
Hart saved from Maddison's shot and Toney fluffed a good chance to pull another goal back early in the second half when his touch let him down and Hart saved at his feet after former Burnley player George Boyd had put lofted the ball over Burnley's back line.
But Rodriguez killed off any hopes of a comeback with Burnley's fourth goal and his second of the game seven minutes into the second half. Lennon's clever pass put him clear inside the box and he slid his shot under Pym and into the far corner. After a VAR check for offside the goal stood.
Posh refused to give in however and sub Ricky Jade-Jones volleyed home from close range after 75 minutes.
Then the lively Toney flicked a cross from Dan Butler just wide as Burnley were kept on their toes to the end, although Hendrick went close to adding a fifth for the Premier League club when his added time free-kick struck the bar.
