The Portugal international stepped up to take a spot-kick in second-half stoppage time after Kortney Hause was penalised for handling in the box.
Aston Villa were leading 1-0 at Old Trafford Hause had fired the visitors into the lead moments earlier – but Fernandes badly missed his spot-kick as he fired high and wide, with Manchester United suffering their first Premier League defeat of the season.
There were some raised eyebrows at Old Trafford when Fernandes stepped up to take the penalty ahead of Cristiano Ronaldo, who many had assumed would take spot-kick duty for the Red Devils following his return to the club from Juventus in the summer.
Fernandes was clearly disappointed by the miss but he took to Instagram on Saturday evening to make a promise to Manchester United fans that he will bounce back as quickly as possible.