The 63-year-old German held his first news conference on Friday as interim manager after watching from the stands as United beat Arsenal 3-2 on Thursday at Old Trafford.

Rangnick's contract calls for him to take up a consultancy role for two years after managing United for the remainder of the Premier League season.

"In the end, to be honest, if a club like Manchester United contacts you for such a role, you cannot possibly turn it down," said Rangnick, whose first game in charge will be Sunday at home against Crystal Palace.

Chelsea had offered just the short-term manager's job, Rangnick said, after it fired Frank Lampard in late January, eventually hiring Thomas Tuchel on an 18-month contract and finishing the season as European champions.

"When Chelsea contacted me last year, or this year in February, they only spoke about the option to become interim manager for four months ... without any perspective to work in the long-term together," Rangnick said.

United fired Ole Gunnar Solskjaer last month after three years as manager and assistant Michael Carrick has stepped down after his caretaker role, making way for Rangnick, who left his role as manager of sports and development at Russian club Lokomotiv Moscow.

Rangnick watched from the stands as Cristiano Ronaldo scored twice in a wild 3-2 win over Arsenal, with the new coach saying the game was "exciting for the fans" but not his preferred style.

"The major target for me in the next couple of days, weeks, is just to bring more balance into the team," he said.

United are seventh, 12 points behind leaders Chelsea, with Manchester City and Liverpool also in the title mix.

"Right now, we have to be realistic. The distance between us and the top three is big," said Rangnick, though he added that "playing for titles" is in the storied club's DNA.

Ronaldo's first goal put United ahead 2-1 shortly after the break Thursday in what Rangnick described as an "impressive" spell by the team.

The German's preferred pressing style - not exactly Ronaldo's forte - will take time to implement.

"You always have to adapt your style or your idea of football to the players you have available, not vice-versa," he said.

"Having seen Cristiano yesterday in the second half, at the age of 36 - amazing, top professional. At his age, I've never seen a player who is still that physically fit. He is still a player who can easily make the difference.

"It's not only about Cristiano. We play in the most competitive league in the world so we need all the players on board. What I saw from Cristiano yesterday, he's more than willing to do that, and the other teammates will have to do the same."

Rangnick doesn't expect any game-changing January transfers but hopes to add "one, two maybe 3 people" to his staff. Carrick has left, though Rangnick tried to persuade him to stay.

He said it was made "very clear" that he's the interim manager but Rangnick didn't rule out recommending - as he did earlier in his career with Leipzig - that he stay on as manager if things go well.

"I'm fully aware that they might be looking for a new manager," Rangnick said. "If they will then speak with me about that, then we will see."

Australian Associated Press