United only earned a return to European football's premier competition after winning last season's Europa League but ahead of the game against Basel on Tuesday night, Mourinho has claimed that the Premier League outfit are back playing in their "natural habitat".
The 54-year-old told reporters: "We're strong, playing well and have confidence in ourselves. It's a difficult game tomorrow but we have the quality to win.
"Being back in the Champions League is going back to the natural habitat. Manchester United [have been there] season after season.
"For some players there's the motivation of playing in it for the first time, so we look forward to the match and I hope also Old Trafford feels it in the same way we are feeling."
United have started the domestic campaign with 10 points for four games in England's top flight.