Erik ten Hag said he is no "Harry Potter" to magic up quick fixes for Manchester United after a demoralising 3-0 home defeat by Liverpool on Sunday.
The Dutchman is already under pressure just three games into the new Premier League season after also losing 2-1 last weekend at Brighton.
A shock FA Cup final win over Manchester City in May helped keep Ten Hag in his job despite finishing eighth last season -- United's lowest ever Premier League finish.
The former Ajax boss was even handed a contract extension and backed with a £200 million ($262 million) spend on new players during the transfer window.
But hope of a new dawn has not lasted at Old Trafford as Liverpool strolled to victory in Arne Slot's first major test since replacing Jurgen Klopp.
"It's not like I'm Harry Potter, that is what you have to acknowledge," Ten Hag said in his post-match press conference.
"We just had a third game in the season, again we have to build a new team.
"We will build this new team, we have young players, also we have now players to build in the season. Today we had two or three players that didn't start of the season and they didn't play 90 minutes.
"We will be fine. It's clear we have to improve, but at the end of the season I'm quite confident that we will have a big chance to lift another trophy."
In one of the most glaring hallmarks of United's struggles last season, Casemiro was the fall guy for Liverpool's first two goals.
The Brazilian twice lost possession before Luis Diaz fired home and the five-time Champions League winner was replaced at half-time by 20-year-old Toby Collyer.
"I think that in football everyone has to take responsibility," added Ten Hag on whether he can continued to field Casemiro given the five-time Champions League winner's decline.
"He's a great character. He has won everything in his career. I'm sure he will keep contributing to our team.
"Casemiro is always winning, so he will be there."
United have not even challenged to win the Premier League in the 11 years since legendary former manager Alex Ferguson retired.
Another season fighting for other silverware already appears the best that they can hope for with a six-point deficit to Liverpool and defending champions City.
"It hurts, especially for our fans," said Ten Hag.
"We have to be humble, we have to give the compliments to Liverpool and we have to move on."