Arsene Wenger feels Sir Alex Ferguson has shown "special qualities" to chalk up 700 Premier League games in charge of Manchester United.
The 68-year-old Scot - who took charge at Old Trafford in 1986 - is set to reach the landmark in the match at Everton.
Wenger's relationship with his old adversary has mellowed somewhat in recent years, the pair having more than the odd bust-up when Arsenal and United battled for domestic supremacy.
The Frenchman - now in his 14th season with the Gunners - has someway to go to catch Ferguson, with 527 Premier League games to date, and paid tribute to the United manager.
"It is dedication and it is a fantastic achievement," Wenger said.
"He deserves a lot of credit to show such consistency at the top level which needs special qualities and special dedication.
"That certainly means 700 sleepless nights before and 700 sleepless nights sometimes after the game!"