Manchester United manager Sir Alex Ferguson says he will miss his personal duels with Jose Mourinho following his riva's shock departure from Chelsea.
Ferguson and Mourinho enjoyed a competitive but friendly relationship
Ferguson, whose team host the Blues on Sunday, added: "He was terrific for football and terrific for Chelsea.
"He brought something fresh and new to our game and I enjoyed the competition with him. I wish him well."
Arsene Wenger, who had several run-ins with Mourinho, added that the former Porto boss was a "great manager".
Ferguson and Mourinho first went head-to-head when the Portuguese masterminded Porto's surprise victory over Man Utd in the 2003/4 Champions League campaign.
Since then the pair have enjoyed a very competitive relationship but one that had an underlying level of respect.
"He enjoyed unparalleled success there, without question," said Ferguson. "It is a big test for whoever replaces him - and at the moment that is Avram Grant."
We didn't get on the best but... that does not hide the fact I respected what he did and the quality of his work
Ferguson added it was important that his players did not allow the story to distract them from the Premier League clash with Chelsea this weekend.
"We have to be focused on ourselves and Sunday's game," said Ferguson.
"We are still playing Chelsea. It is still the same players and that in itself is a challenge for us.
"If you look at the record between us over the last three or four years, there is nothing in it."
Wenger, despite the much-publicised disputes with his London adversary, has also paid tribute to Mourinho's achievements.
"He arrived when Chelsea were on the way up... they had a good side already and he did something more and made them winners," said the Arsenal boss.
"He deserves a lot of credit for that because it is never easy to win and in England it is maybe more difficult.
"We didn't get on the best but recently it has become better. That does not hide the fact I respected what he did and the quality of his work."
You know my relationship with him, it is better that I do not say anything
Mourinho infuriated Wenger when he described the Frenchman as a "voyeur".
In response, the Gunners boss said of Mourinho: "When you give success to stupid people, it makes them more stupid sometimes and not more intelligent."
But Wenger insisted he had immense respect for the way Mourinho transformed Chelsea one of Europe's most powerful teams and won back-to-back Premier League titles.
Wenger added he felt he and Mourinho had always been closely matched as coaches.
"I feel we were very close and we have to accept that they beat us a few times and they were better than us a few times in the last three years," said the Frenchman.
Asked about Chelsea's immediate future and the possibility they would be weakened by the loss of their charismatic coach, he replied: "Time will tell."
But he was quick to praise new Blues boss Grant, promoted from director of football to replace Mourinho.
"He is a very intelligent man with a big knowledge of the game so he will adapt," said Wenger, whose table-topping side entertain Derby on Saturday.
Unlike Ferguson and Wenger, Liverpool manager Rafael Benitez declined to comment at all about Mourinho.
The pair have clashed several times, notably during the Champions League semi-finals in 2005 and 2007.
Benitez also frequently suggested it was Roman Abramovich's billions that bought back-to-back Premier League titles for the Blues rather than Mouinho's genius.
"You know my relationship with him, it is better that I do not say anything," said Benitez. "At the moment I am more worried about Birmingham boss Steve Bruce."
Liverpool face Birmingham at Anfield on Saturday.