Just in case Chelsea fans weren’t already aware that it was a big mistake to allow Kevin de Bruyne to leave the club back in 2014, the Belgian served a timely reminder on his return to Stamford Bridge on Saturday evening.
With the scores still level at 0-0 during the heavyweight clash between Chelsea and Manchester City, De Bruyne picked up the ball 25-yards out, played a one-two with Gabriel Jesus and smashed the ball home with his left foot.
And it was just a snippet of De Bruyne’s incredible ability.
The 26-year-old has established himself as one of the best midfielders in European football and is worth a lot more than the £18 million the Blues received for him from Wolfsburg.
Even the egotistical Jose Mourinho must admit that he made a big mistake by allowing him to leave Stamford Bridge.
While the Portuguese boss didn’t doubt De Bruyne’s ability on the pitch, it was his performances in training that disappointed him. The Special One questioned De Bruyne's commitment in sessions and rarely gave him first-team opportunities.
But the player himself didn’t agree.
Why De Bruyne wanted public training sessions
And, in an interview earlier this year, De Bruyne explained why he wanted to have public training sessions at Chelsea - so Mourinho couldn’t point any fingers at him in front of the thousands of people watching.
“It is true that he said that in the press, yes,” De Bruyne told France Football on the criticism aimed at him by Mourinho.
“That I wasn't doing what was needed in training. It was easy to say that because there was no-one to check it – the training sessions were closed to the public. But everyone knows I am not like that.
“I never let anyone put me down. I say what I have to say, with respect of course. But at that moment, I couldn't do anything because he would have said I was lying and afterwards he would have used it.
“Did I ask for training to be done in public? I said it, yes, but not to him personally.”
And former Chelsea scout Piet de Visser has explained what Mourinho told him when De Bruyne eventually left the club.
"I was angry with Mourinho when De Bruyne left Chelsea," De Visser told HLN Sport.
"We had some discussions. Then he would say: 'Piet, I find it a shame too, but the boy wants to leave. He doesn't want to train under me anymore.'
"I told him: 'Yes, the boy wants to play. He's ready for it.' I have tried to convince him of Kevin's qualities. But then Mourinho repeated: 'Piet, he doesn't want to train."
After securing a massive victory against his former side, De Bruyne revealed that neither he nor Chelsea have any regrets over his departure three years ago.
"I've no regrets over anything that happened," he said.
"I don't think they have regrets -- they've won two league titles since I've been gone, so they've done fairly well.
"That's the way it goes, it's a business. At that point it was a good decision for me to go and maybe for them it was also good to let me go.
"There's no bad feeling at all. It's just part of life and you need to grow up."
While Chelsea have won two league titles in recent years, there is very little doubt they will be regretting letting De Bruyne leave so easily.