Barely a month into his Old Trafford career and the Senegal international already has his first Premiership goal, a reserve-team hat-trick and praise from his manager.
But when the news first broke, Sir Alex Ferguson's move for the former Molde striker was greeted by great surprise in Norway.
"We had no intention of signing anyone else after Gabriel Obertan," Ferguson said. "We felt we had done our business, but the situation accelerated to the point where other clubs were bidding, so we had to make a decision."
Ferguson had made the announcement while in Singapore, having signed the striker sight unseen and on recommendation from his reserves coach and former United and Molde star Ole Gunnar Solskjaer.
Just three weeks previously, former Norway coach Nils Johan Semb had dismissed Diouf's chances of making an immediate move to a top tier competition.
"I cannot see Mame Biram Diouf being ready for a top league," said Semb. "It is almost unimaginable in the Premiership to see a player miss, then miss and then miss again!"
Upon Ferguson's announcement, Semb stood by his comments.
"Look, he has huge potential. They've invested in him because of that. He is young and has speed and skills. Alex Ferguson is good at picking players with development potential, and turning them into top players.
"Ole Gunnar Solskjaer is of course the most obvious example.
"Because of his speed and skill he comes to have very many chances. But he must develop his repertoire and become a better finisher."
But it wasn't just Semb who was surprised, even Diouf's Mum needed some convincing when Mame first called her about the news.
"I called home and everyone - as usual - thought I was joking!" laughed Diouf. "But Mum knows me well and eventually she knew I was telling the truth.
"Soon the media in Senegal made everyone aware of the story and my home was visited by friends and family for a big celebration."
It's great reward for Diouf's parents, who funded his trip to Norway and enrollment at Molde Folkehøgskole college. It was there, with fellow Senegalese and former Molde teammate Pape Pate Diouf, that Mame did enough to convince Molde coaching staff to hand him a pro deal.
Øyvind Reinertsen, a coach at Molde Folkehøgskole, recalled: "I know Mame well. He was first visiting Pape once in the spring, but was a student here in the autumn of 2006. Both made a quick transition to the Norwegian culture and quickly became a part of the environment with us."
He added: "Mame has an incredible leap, does spectacular things and scores from all possible angles. He is the most perfect athlete I've ever seen. He was good in all ball sports."
And on the move to United?
"It's totally crazy! I thought he wanted to go to France because of the language. This was surprising, and incredibly fun."
"Fun" is also how Molde chairman Leif Arne Langøy described the deal.
Langøy takes great pride seeing three former Molde players now involved at United. Along with Diouf and Solskjaer, Magnus Wolff Eikrem is also establishing himself at the Premiership giants.
"To have this relationship with United we believe is a real scoop," says Langøy. "There's no other (Norwegian) club that can boast three sales to them."
From Dakar to Molde and now Manchester, Diouf has vowed to stay grounded as he begins his new life at United.
"I will miss my walks in Storgata here in Molde. But I guarantee to be as open and down to earth in England as I am here in Molde," he said.
"What has happened to me is fantastic and I owe all of Molde a big thank you for the opportunity I have been given."