The Red Devils capitulated at Stamford Bridge to lose 4-0 after conceding twice in each half in what was a homecoming to forget for the former Blues boss.
The loss means United sit in seventh position on the Premier League table with 14 points from nine game, some six points behind leaders Manchester City, Arsenal and Liverpool, and Mourinho is desperate to fight back with some much-needed victories after a tough week.
"In terms of points, it's zero points - if you lose 1-0 or 4-0 you lose three points. We are six points from the top of the league and now we have to win matches," he said.
"We had a week where we have played two (title) candidates in Liverpool and Chelsea and now the other teams from the top five have to play among themselves, they have to draw and lose the points each.
"We need to win our matches now, which is not easy but we play Burnley, we play Swansea and West Ham and we need to win matches to close the gap."