Pogba, who is celebrating his 26th birthday, pledged to donate £26,000 to a charity which provides drinking water to those in need.
And Phelan praised the World Cup winning midfielder for his efforts with a simple message on social media.
Phelan replied to Pogba with: “Good lad PP” followed by a thumbs up emoji and one of a football.
And Manchester United fans were loving the response from Ole Gunnar Solskjaer’s assistant.
One posted: “He is!! Love that you comment like this Sir Mike Phelan”
Another added: “big mick knows best compliment you can give is good lad”
A third commented: “Never leave Mike”
And a fellow United supporter wrote: “God I love Mike Phelan”
Phelan has been key to Ole Gunnar Solskjaer since the Norwegian took charge of Manchester United in December.
Solskjaer has won 14 of his 18 games in all competitions since replacing Jose Mourinho.
Solskjaer is only in caretaker charge until the end of the season, with it unconfirmed who United’s next permanent manager will be.
The former striker appointed Phelan straight after getting the interim job and Robbie Savage believes Sir Alex Ferguson’s former right-hand man has been key to Solskjaer.
“Paul Pogba looks the best midfield player in the world, Marcus Rashford looks like the exciting kid who burst onto the scene three years ago, Ander Herrera looks reborn and Victor Lindelof looks the part now too,” Savage recently said.
“The evidence of United’s transformation under Solskjaer is all over the pitch.
“But I repeat: There’s no point in giving him the job now. In terms of winning trophies, nothing has changed.
“From the shambles of December, when one the world’s biggest clubs was reduced to installing an interim manager in mid-season, he has proved an inspired appointment.
“But I would also give huge credit to coach Mike Phelan, whose technical influence should not be underestimated.
“Of all the mistakes in the recruitment and release of managers and backroom staff since Sir alex Ferguson’s retirement six years ago, cutting Phelan adrift was the most damaging.
“When the time comes for the board to stick or twist with Solskjaer, I hope Phelan has a part to play in United’s future.
“He understands the club’s DNA and the style Fergie inspired.”