The Frenchman came on as a 65th minute substitute, replacing Juan Mata and put on a stunning performance on his first appearance for Man United.
Martial beat two defenders before cutting inside and calmly finishing past Simon Mignolet at the Stretford End for a brilliant solo goal and van Gaal was happy for the youngster.
He said after the game: “The goal of Anthony was not a bad goal, I think! It was a good match for him because Liverpool had to come [at us] so he had a lot of space. It was more easy to bring him on but he did alright.
“He scored a marvellous goal and I have seen also that, physically, he can play in the Premier League. And he can dribble as you have seen.”
Despite all the attention being on the striker, van Gaal is wary that he is still young.
He added: “I am very happy for him. But we have to say, he’s 19 years old and he’s out of France and it is very difficult for a 19-year-old player to adapt to the culture of England, the Premier League and the high rhythm of the game here but he has a great talent and he can improve.
“He shall get better and better.”
It is encouraging for United fans to hear that the youngster will only get better with time. Even though he is still young, Martial gave Old Trafford a glimpse of what he is capable of.
Given the astronomical fee Ed Woodward paid to secure his services, a lot is expected and Martial has already started to justify his price-tag.