The world No 7's court coverage was amazing. She showed incredible pace to get to balls most players would never be able to reach, and did more than that, often blasting unthinkable winners from impossible positions on the run.
Williams was a set down before she knew it and despite every effort to bounce back, could not stem the tide as a ruthless Halep surged onwards to claim a memorable victory.
"She literally played out of her mind," Williams said. "Congratulations, Simona.
"It was a little bit like a deer in headlights for me.
"When a player plays that amazing you have to just tip your hat to her."
If Williams was shocked, so too was everyone else.
Commentators and former players were stunned by Halep's onslaught as she rocketed to a 4-0 lead in just 11 minutes.
Williams managed to get on the board but in 26 minutes she was down a set and half an hour later the match was over.
The first set demolition took people's breath away and it continued in the second as Halep finished with just three unforced errors to Williams' 26.
"A shocked crowd as well as commentators right now to see it this one-sided," tennis legend John McEnroe said in commentary for the BBC.
"What an unbelievable first set from Halep."
Former British star turned commentator Sam Smith was in awe of Halep's ability to seemingly be everywhere on court as she chased balls like a terrier.
"Her dad and brother (in Halep's box) can hardly believe this start. It's as if Serena's playing two Simona Haleps down the other end," Smith said
Ex-American player Tracy Austin said everyone was "stunned". "It's incredible, so much credit to Halep … she really just took the first set and Serena was so uncomfortable because she is used to dictating play."
BBC 5 Live radio commentator and former British No 1 Annabel Croft added: "It's kind of taken my breath away, to be honest. I didn't expect this to happen."
Halep was adamant she played "the best match of my life" and it wasn't just her who was emotional about achieving a lifelong dream. Her mother, who always hoped her daughter would one day grace the famous grass courts of Wimbledon, was too overwhelmed to even speak.
"She didn't say anything because she was crying," Halep said. "I just hugged her and I kissed her. I knew she's very emotional. I just told her that we'll talk later.
"It feels good. I wanted this badly. When I started the tournament, I talked to the people from the locker room that my dream is to become a member here. So today it's real and I'm really happy.
"I'm really proud of my game of today and the whole tournament."
Halep admitted she'd been intimidated by Williams in the past so decided to be aggressive from the outset and it was an approach that paid dividends as she reeled off 13 winners.
Trying to describe how she felt the moment she won the match, the newly-crowned champion said it was simply a "beautiful" feeling.
"I felt my legs that are very soft after I won the last point. I didn't know actually how to react. I just did natural what it came in my inside," Halep said.
"Yeah, it's tough to describe the moment. You just feel, like, light, you feel everything. It's beautiful, and you just try to enjoy. It's tough to say."
Williams cut a sombre figure in her post-match press conference, but didn't believe she could have done anything else to change the result because Halep was playing that well.
She's now lost her past three grand slam finals and equalling Margaret Court's record of 24 major singles titles will, once again, have to wait.
"She just played great. So I don't think it's a surprise for anyone to play great against me," Williams said.
"She was getting so many balls back. I do have a strategy for players that do get a lot of balls back, which I thought about far too late. I think I was over-hitting it, trying to go for too much. She was getting just a tremendous amount of balls back.
"I think for me any loss is not easy, per se. Like I said on the court, when someone plays lights out, there's really not much you can do. You just have to understand that that was their day today. Hopefully they can play like that more often, more consistently.
"Hopefully I can raise the level of my game sometimes.
"I don't know if there's anything I could have done differently. I think I gave a great effort for this fortnight. Again, I just think Simona just played her heart out. If anything, I could just learn to be like that."
At 37, questions will understandably be asked about whether Williams will ever win another grand slam, but she maintains she hasn't given much thought to the possibility she won't add to her incredible tally.
"It's different. Now, you know, in my 20s … I'm always expected to win, but it's a different circumstance for me," Williams said. "Seems like every grand slam final I'm in recently has been an unbelievable effort to get there.
"It would be interesting to see how it would be under different circumstances.
"I don't really think about it (getting harder to win as she gets older) really. I just go out there and play, see what happens. That's kind of how I've been in my whole career. You know, I never thought about time in general.
"But, yeah, I don't know. I don't think it's harder. I think it's just, you know, coming out there and doing the best that you can do. That's really all you can do."
