Kelly, who made his full debut against Lyon in Glen Johnson's injury-absence, said: "If we can beat United, it will give everybody a lift.
"I was pleased with my debut, but everyone was disappointed about the result. It was a cruel way to lose like that right at the end, I was off injured by then and watching on the TV and I didn't feel they were going to score again after their equaliser.
"I enjoyed the occasion even if I had to come off. But it was just one game for me, I want to be playing at this level every week. That's the aim now.
"Now we just have to look forward to Sunday's game with Manchester United and try to put things right.
"It is all about working hard as a team now to pull ourselves out of this."