The Argentina international hit a screamer in the first-half, with Mac Allister later saying it was the best of his career.
"I had a nice one against Leicester [for Brighton] but it was disallowed," he told liverpoolfc.com. "So I think it was the best goal I scored in my life.
"Not a bad start to my career there in Liverpool as a goalscorer!"
He continued: "As soon as I hit it, I knew that it was going to be a goal.
"[It was a] very nice goal, but as I always say, when I play as a No.6 I am not very worried about goals and assists [because] I have other work to do - but it's always nice to score!"