Raul Jimenez had the hosts ahead midway through the first-half before Ings found a 95th minute equaliser for West Ham.
Lopetegui later said: "It was a very ‘Danny Ings’ goal!
"He is always agile in those kinds of actions, and he took his chance very well.
"I’m really happy for him, because he hasn’t played much up until now, but he is always ready to go. He is a really good example to all of his teammates, and it’s great to see his work pay off.
"As a player, it can be hard when you don’t know when the coach is going to call you. The important thing is to try and always be ready, because you are going to be needed at some point.
"Scoring in the last minute today is important, because he’s shown everyone that you have to believe until the end. Even though there were things we could do better today, we kept going and we got something out of the game.
"We are happy in the end, but I think there are lots of things we can improve.
"The belief and the effort was good, but it was a tough match today and we could have done certain things better.
"I know playing Fulham at their home ground is always hard, and they were good today. But at the same time we can do better, and we will work on a lot of things ahead of the next game.
"One important thing we did do well was keep it to 1-0, and not let Fulham score again.
"The second goal in a match is so important so often, because it can kill or close a game.
"I think we had spells in the first half, but they were better despite not having too many clear-cut chances. But it’s true that in the second half we were better, and the changes we made balanced things.
"We pushed forward and the players kept fighting and believing, and thankfully we got the goal we wanted when it mattered."