The former AC Milan and Juventus striker scored in successive Premier League appearances with the opener nine minutes before half-time after the 34-year-old rose above Euro 2016 winner Jose Fonte and placed a header past England goalkeeper Fraser Forster.
The former Paris Saint-Germain centre-forward, who completed a free transfer to the 20-time English champions earlier this summer, added his second from the penalty spot after ex-Southampton left-back Luke Shaw was fouled inside the area.
Mourinho brought on another summer signing Henrikh Mkhitaryan in the second half but the Armenia international couldn’t find the net as Pogba completed the full 90 minutes of United’s second Premier League game.
United are at the top of the Premier League table and three points clear of second-placed Liverpool following their comfortable win against the Saints.
Here is a round-up of the best Twitter reaction from the professionals, past and present, in chronological order to United’s comfortable victory over Southampton.
Come on then let's see what we've got !!! Buzzing for tonight zlatan to score ⚽️⚽️
— David May (@DavidMay04) August 19, 2016
Looking at Pogba and Fellaini as a partnership interesting to see that they are both taking turns in going forward. No designated sitter.
— Danny Higginbotham (@Higginbotham05) August 19, 2016
Only had Zlatan for a brace! #punditry
— Stan Collymore (@StanCollymore) August 19, 2016
That bloke isn't bad for a free transfer!! #Zlatan
— Matt Le Tissier (@mattletiss7) August 19, 2016
Mmmmm United look very good again
— Peter Crouch (@petercrouch) August 19, 2016
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