With the Red Devils' unbeaten start to the Premier League season under threat following Kortney Hause's goal at Old Trafford, Fernandes had a last-gasp opportunity to rescue a point for his side from the spot on Saturday.
However, the Portuguese blasted his penalty over the bar as United succumbed to a 1-0 defeat on home soil, but he has vowed to make his teammates and the fans proud over the rest of the season.
Fernandes wrote on Instagram: "Nobody is more frustrated and disappointed than me for missing the penalty and the consequent defeat.
"I've always assumed my responsibilities and I've always embraced them under pressure in moments like this. Today, I failed. But I took a step forward and faced the challenge with the same ambition and responsibility as when, on the many other occasions, the ball ended up in the net.
"Criticism and contrasting opinions are a big part of football. I've learned to live with it, even using them to drive me on, and I consider it all a very important part of my commitment to never stop trying to improve and to become the best player I can possibly be, for me and the team.
"Today I once again took the responsibility given to me almost since I joined United and I will take it again without any fear or dread whenever called upon. The most important thing for me is to win together and I'll always do everything I can to help my teammates and the club to be the best we can be.
"I'm a player who leaves everything on the pitch, with great desire and commitment. And that's what I'll continue to do. Thank you for all your support after the final whistle! Hearing you chanting my name in the stadium was very emotional... I will come back stronger for me, because these are the standards I hold myself to, but most of all for my teammates and our fans who have always supported us."
Fernandes still boasts an impressive tally of four goals from his opening six games of the Premier League season and will hope to make amends when United meet Villarreal in Wednesday's Champions League clash. body check tags ::