Jesse Lingard is "hurt" by Manchester United 's defeat to Young Boys and his error that led to the Swiss side's winner.
Ole Gunnar Solskjaer's men suffered a disappointing loss to open their Champions League campaign as the hosts claimed all three points in stoppage time.
The Red Devils were in a promising position after Cristiano Ronaldo fired home a first-half opener, but Aaron Wan-Bissaka's red card changed the game entirely.
Young Boys were on the front foot from that point as United tried to defend their lead.
Moumi Ngamaleu scored an equaliser before they were eventually rewarded for their dominance as Jordan Siebatcheu sealed the victory with a dramatic winner in stoppage time after Lingard's costly error.
Jesse Lingard made a costly error ( Image:
Rex)
The Man Utd midfielder, who came on for Ronaldo with 20 minutes to go, misplaced a back pass to David de Gea in the 94th minute as Siebatcheu got on the end of it to secure the 2-1 win.
And Lingard says he is upset for his mistake but has vowed to respond to the setback as United take on West Ham on Sunday.
He said on Instagram : "Last night hurt. Every time I pull on the United shirt, I hope people understand what it means to me. I always go out wanting to do the best for the club, the team and especially the fans.
"I'm upset for my part in the defeat. I never want to lose any game but mistakes happen in football and we now push on together. We will all pick ourselves up and I can't wait for Sunday."
Lingard's teammates have given their support to him following the post.
Bruno Fernandes said: "We lose together and we win together."
Paul Pogba added: "The true measure of success it's how many time you can bounce back from failure.. we strong, bro."
Diogo Dalot, who replaced Jadon Sancho after Wan-Bissaka's red, said: "Always with you. We win and lose together."