Simon Cowell's 'Mr Nasty' side returned at The X Factor bootcamp this series.
The X Factor 2017's bootcamp auditions were held at Wembley Arena earlier this year.
For the first time in a good few years, there was an audience present to watch the performances alongside the judges.
And they saw Simon laying into some of the less than talented contestants, the Daily Mirror reports.
Harsh putdowns from the music mogul apparently included telling one act: "You’ve let yourself down. It looks like you don’t care and you didn’t come here to win."
A source told the tabloid: "He has never lost his focus but Simon has definitely been more relaxed in recent years. But when things went wrong this weekend the old acid-tongue and killer putdowns were back
“He is very excited about the talent on the show this year but he is a perfectionist at heart and wants to make sure the right people go through so he didn’t hold back.”
This year's bootcamp is split into two parts and will start off with the so-called 'wall of songs' which first made its debut on last year's series.
Contestants will face a wall which has a number of pieces of paper with songs attached. Each song appears a number of times on the wall.
On a signal, the acts race towards the wall and fight for the song choice they want. The contestants that have chosen the same song will then group up to work on their performance of the track before taking to stage to sing for the judges.
The judges will then decide on the spot who will progress onto the second stage of Bootcamp, the arena auditions.
There the acts will each take to the stage once more but this time it won't just be the judges watching on as - for the first time this series - the contestants face a live audience at Wembley Arena.
The X Factor 2017's bootcamp double bill airs starting this Saturday between 8PM and 9:30PM.
The show continues with a bumper episode on Sunday night from the earlier time of 7:30PM, finishing at 9PM.