Harry Kane scored for Spurs after his return from injury.
The England striker missed two and a half games with an ankle injury he endured in the match against Liverpool.
He was expected to be out for a few weeks but came back after only 10 days.
The England captain scored his 13th Premier League goal against the Baggies after his return from injury.
“He is one of the best strikers in the world. Period,” Mourinho said.
“There is nothing else to say. The team depends a lot on him, we can’t hide that.
“It’s the goals he can score, the assists he can make, the link play he has, that personality that players like that can have and he is always an important influence for us.
“Today I was promising I was not going to speak about individuals because I am so happy with the compromise of the players to win the game and close this negative series of three defeats, but with the question it is hard to run away from it. He is a very important player.”
Mourinho added: “Yesterday he was training absolutely fine, perfectly normal. Of course a player of his level, he has the experience to make his own decision. Can I play, can I be on the bench, can I start the game?
“He was clear, he was ready to do it and he did the game without any problem.”