The Black Cats took the lead through a first-half striker Darren Bent, but Pompey managed to get a draw in stoppage time after a goal by Younes Kaboul.
“Not many times in my life am I happy with a point, but when we score in the last minute it is good,” said Grant.
“But on our second-half performance I think we deserved it.
“We wanted to start quick and play different, but sometimes in football things happen which you can’t explain but in the second-half we dominated the game and created more chances.
“I think when you’re at the bottom of the table, you need to show spirit and belief, if you don’t then you will stay in that position and we don’t want to.”
Pompey are still five points adrift of safety following Wovles’ win at Tottenham.
“I don’t think it will be easy, it will be very difficult, but it is possible. We need to continue to believe and I am very happy that we have showed this in the last two games,” Grant said.
“We know how to play football and there is no team around us that plays better than us, we knew we had to play with more intelligence and more spirit and we showed that today in the second-half.
“We have taken four points from the last two games and that is the first time we have done that this year and that is important and that is good for us and we have to continue with this.”
