Pep Guardiola hinted Manchester United may have been guilty of over-confidence ahead of their Champions League defeat against Paris Saint-Germain last Tuesday, after his Manchester City side beat Newport County 4-1 in the FA Cup fifth round.
On a bobbly pitch at Rodney Parade, Irishman Padraig Amond scored another FA Cup goal as League Two strugglers Newport battled bravely against the reigning Premier League champions, but it was not enough to halt City's march.
Two goals from Phil Foden sandwiched strikes from Leroy Sane and a late clincher from Riyad Mahrez, yet Guardiola's decision to use United's defeat against PSG as an example of a side showing over-confidence ahead of a big game may raise a few eyebrows.
"The big mistake is believing you are better than anyone," said Guardiola. "It is a mistake, like United are praised and they say they better than PSG, but you see what happened. You have to be calm and prepare well.
"This was a really tough game, we opened the scoring in the game and believed it was done and then they scored. Phil (Foden) scored a fantastic goal. They showed us how incredible they are and a big compliment for them.
"The first 20 minutes were difficult from throwing and long balls and they are much better than us in those situations but in the last 20 minutes we put the game into our hands and the goals help us to win the games.
"The home crowd was amazing, winning here, I realise English football today better than ever and how tough the cup is in these conditions. They use their points where they are better than us. That is why I am so delighted with how we have played here today."
Guardiola would not be drawn on suggestions his side could win all four competitions they are still competing in as he faced the media after his side's latest win.
"We don't talk about winning four trophies, not at all," added Guardiola, whose side now face a week that will include a Champions League last-16 game against Schalke in Germany and the Carabao Cup final against Chelsea at Wembley next Sunday.
"We will see in May and June how we do, but it is important to be there in all competitions in February. The result will be shown at the end and now we have to recover and prepare for our trip to Germany.
"We are in four competitions - every game is completely different. You play League Two then Champions League. You have to be calm and prepare well."
City's man-of-the-match Foden claimed the Rodney Parade pitch was the worst he has ever played on, as he reflected on his impressive display.
"It was the worst conditions I have played in," said the City youngster. "We had to show professionalism and keep the ball moving and they tired in the end. We scored straight away after they scored. It's a big squad and everyone wants to show the boss they can start. He rotates the squad a lot and he gives people a chance.
"It was a difficult pitch and we kept playing our football and our quality shone through. It's always special when I score for the club I have always supported. I try and get as many as I can.
"The opponents got tired and the space started opening up and the chances came and we managed to take them. Our defenders dealt with every ball well today and we showed our quality on a difficult pitch. We scored straight after they did and it is always good to take the pressure off and get the goal.
"Everything is going well at the moment and we can definitely win every competition, but it is going to be difficult. I'm trying to take my opportunities as they come."
Murray Wallace's early header ensured that Millwall be in the quarter-finals of the FA Cup for the second time in three years and ended AFC Wimbledon's record-breaking run in the competition.