Chelsea ended Mourinho's six-year exile in Italy and Spain yesterday when they reappointed him manager and he will be officially unveiled at a press conference at Stamford Bridge next Monday.
While the Portuguese's first reign ended in acrimony after his relationship with owner Roman Abramovich soured, his arrival heralded the start of the most successful period in the club's history.
The summit of his achievements were Premier League crowns in 2005 and 2006, and his track record of domestic success - he has also won championships in Portugal, Italy and Spain - have raised expectations he will break the three-year duopoly of Manchester United and City.
But Mourinho believes that although no English team progressed to the quarter-finals of this season's Champions League for the first time since 1996, club football in this country remains highly competitive.
"The Champions League is a thermometer of world football and English football was out of the competition too early," he told Chelsea TV.
"People were speaking about the level of the Premier League going down compared with other countries, but I don't believe that. Sometimes things happen when there are no reasons.
"But the Premier League is still a fantastic competition and I believe five or six teams are very strong.
"When I was here before it was more about us, Man United and Arsenal and after that there was a gap to the other teams.
"Now you can put five or six teams in the same plan, aiming to reach the Champions League spots which is very difficult, with those with more ambition aiming to win the Premier League. The competition will be fantastic and I hope I can beat the other clubs."