The Red Devils comprehensively dispatched Newcastle 4-1 and Cristiano Ronaldo, who received a hero's welcome for his return to the Theatre of Dreams after 12 years, capped off his second debut in style with two goals.
Bruno Fernandes and Jesse Lingard also scored sublime goals, with Paul Pogba grabbing two assists to continue his dazzling start to the new campaign.
There was something different about United on Saturday - Ronaldo not only did the business on the pitch, he appeared to have ingrained a new level of confidence in his teammates as they put the Magpies to the sword.
And the attractive brand of football on show has won over former Tottenham midfielder O'Hara, who wants to see the Red Devils win the Premier League title now that the football phenomenon has returned.
Speaking on Monday's talkSPORT Breakfast, O'Hara waxed lyrical over United's performance.
"I've never been so excited to watch a game in a long, long time and it felt like the Man United of old," he said.
"It was nostalgic. It really was. I grew up and Man United were the best team at the time with Ronaldo and Rooney.
"It was almost like watching that again, I really enjoyed it."
O'Hara insisted Ronaldo looks as good as ever, even at 36, and has been reinvigorated by his return to Old Trafford.
"I watched him at Juve and he was very much sort of, not static, but very much in and around the box. getting on the end of crosses, scoring penalties," he added.
"For Man United he was everywhere. He's loved there and knows what it's like to play at Old Trafford, it's his home.
"The way he was going past players, chopping players, showing his pace. I was thinking 'wow', 36 years of age. It was incredible to watch."
He added: "It looked to me like the old Man United were back.
"I have to say, I know I'm a Spurs fan but Spurs are not going to win the league.
"I actually want Man United to win the league because that nostalgic feeling I had was brought all back watching them."
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