Arsène Wenger has paid tribute to Sir Alex Ferguson's "unique achievement" ahead of the Manchester United manager's 20th anniversary in charge.
On Monday it will be two decades since the Scotsman took up the reigns at Old Trafford. Wenger has just celebrated 10 years at Arsenal and has always enjoyed a highly competitive relationship with Ferguson.
"Yes I have seen half of those 20 years from very close up," said the Frenchman in Friday's press conference. "When you think that the average life of a manager [in the Championship] is one year and 11 days, and yet he has done 20 years then it is remarkable consistency.
"It is also remarkable achievement and a unique one in Europe at the top level. No one could say the opposite. To do something like that needs tremendous motivation and stamina, and he has had that."
Wenger also suggested the passing years has mellowed their relationship.
"With us two, it was about competitiveness," he said. "I am competitive and I don't like to be beaten. Yes, we have had some heated times but time settles things and there is a respect there now."
Copyright 2015 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source