Hernandez scored the winner with five mintes remaining of the Champions League tie, after coming of the substitutes’ bench.
“He is a fantastic finisher. He took his goal as if he was shelling a pea, it was so natural to him,” Ferguson told Sky Sports.
“His pace and his penetration caused them a bit of bother.”
He continued: “I think it was an important win.
“Obviously Valencia and ourselves were favourites before the group stage started. So to get a win over them was really important.”