It was thought that Man United would trigger a one-year renewal clause in Pogba's contract but only to retain the midfielder's market value.
Pogba's current deal expires next summer and the Red Devils are keen to sell, hoping to do a deal for £100m.
The Old Lady, who sold Pogba to United for £89m in 2016, are reported to be extremely keen on a reunion with the Frenchman.
The shirt read 'Matuidi' on the back and the 27-year-old insisted it was in support of his French teammate Blaise Matuidi who was diagnosed with COVID-19 this week.
"I am positive," he wrote.
"Usually I like to think I'm positive. Someone who tries to radiate good waves around him, my family, my friends, my team-mates.
"I am positive, we will come out collectively stronger from this test, it will teach us to know each other better, to be more united, more generous, better."
Solskjaer's Real Madrid counterpart Zinedine Zidane is a big fan of Pogba and spoken of his admiration for the player in the past.
It's the midfielder's fitness struggles that have caused his value to drop from an estimated £150m.
