Marc Cucurella struck in the second-half as the Blues won at Stamford Bridge.
"It was a much-needed win, it was all or nothing to keep it in our hands," said James afterwards. "Manchester United set up well and made the first half very tough. We knew going into half time, we needed to come out, create a few chances and take one.
"It's tough when you need to win, when they come here and make it difficult. We need to ignore where they are in the table because it doesn’t reflect how good they are. I think we saw that today. They made it tough, but we’re happy to get the win."
Cucurella combining well
James continued: "I knew that I had space and time, and if I put it in the right area, then Marc is always arriving, so I’m happy we were both able to contribute to the win today.
"What makes the difference in the end is the goals. They didn’t have many chances; they had one offside goal, but they didn’t have much other than that. As a team, we’re getting stronger and I think we showed that today. We’re stepping up as a group.
"I’m pleased. I know we got what we wanted today, but the game is finished now. We have to get rest, recover and know we have two more huge games, and we need to win both."