Luke Williams avoided being the first Peterborough boss to fail to make the second round of the FA Cup in 20 years with a 1-0 victory in his first game in charge of the club over Cardiff.
Harry Leonard scored the only goal of the game as Williams endeared himself to the London Road faithful at the first attempt.
Matchwinner Leonard squandered two brilliant chances in the first five minutes as he twice failed to hit the target.
Posh stopper Alex Bass produced a good save to keep out Callum Robinson after uncertainly at the back for the hosts.
But Leonard was in the right place at the right time to break his duck for the club as he slotted home in the 38th minute.
After the break, Bass pulled off another good stop to keep out Cian Ashford’s effort.
Ashford also missed a good chance when he volleyed over unmarked at the back post on the hour.
Brandon Khela could have wrapped up the game with 10 minutes to go but Nathan Trott easily kept it out.
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