Lewis Hamilton said Niki Lauda's spirit guided him to the toughest win of his career in Monaco.

Hamilton pointed to Lauda's name, which graced the back of his one-off red helmet, after he fended off Red Bull's Max Verstappen to claim a nail-biting victory - his third on Monte Carlo's famous streets.

Lauda, Mercedes' non-executive chairman, died on Monday, aged 70. Hamilton, whose team all wore red caps in tribute to Lauda, said he planned to phone the late Austrian's wife, Birgit, on Sunday night. He also confirmed he will attend Lauda's funeral in Vienna on Wednesday.

Hamilton was left to masterfully tiptoe his way to the end after a strategy error left the Briton on less durable tyres than his rivals.

He even survived a late collision with Verstappen when the young Dutchman launched a gung-ho move for victory with three laps to go.

Relieved and wearing his Mercedes race suit, as well as a red baseball cap emblazoned with the word 'Niki', Hamilton then celebrated his win by back-flopping into the swimming pool.

After towelling down, he reflected on an emotional win.

"I definitely felt like Niki was racing with me," said Hamilton after the 77th win of his remarkable Formula One life.

"That was for you, Niki. Your fighting spirit was right there with me every step of the way. I know he was looking down and taking his hat off to us.

"It was the hardest race I have ever had, it was the biggest challenge I have had. It has been such a hard week, emotionally. I just wanted to do the job and deliver for Niki. When I was driving, I was like what would Niki do?

"As a driver, my goal is to be respected as Niki was. He was a hero to so many.

"I cannot wait to give my dad a call and see what he made of it. I am sure I will get a chance to speak to Birgit after the race, too - to let her know how much I appreciated her support. She kept us connected."