Many thought Dalglish would skip the Cup tie and wait for their clash with Blackpool to take charge.
But he told liverpoolfc.tv: "When somebody is in trouble at the football club, it's your job to help them. I suppose in some ways it would have been easier not to be involved with Manchester United but I felt it was important for myself to turn up and stand beside the boys even though they were well prepared with Mike Kelly and Sammy Lee.
"I felt it was right for me to be there. We're all in this together and we are going to see it through together."