Arsenal manager Arsene Wenger criticised the rash of sackings in English football on Friday, saying coaches needed time to put their ideas into practice.
Wenger's comments came before facing his oldest rival Alex Ferguson in Saturday's clash with Manchester United and a week after fan-favourite Martin Jol was sacked by north London neighbours Tottenham Hotspur.
Asked about the string of managers who have already lost their jobs this season, Wenger said: "I think it is terrible.
"It is very bad for football, for the game.
"If you have a vision in football you need time to get that into the club. Once that doesn't happen any more the consistent progress and the improvement of football (at the club) becomes impossible.
"It's also usually very bad news financially for the club too," he told reporters at Arsenal's London Colney training complex.
Wenger recently celebrated 11 years at Arsenal while Ferguson marks his 21st anniversary of becoming United's manager next week.
Both men have gone seasons without winning a trophy, but survived in their jobs while many of their rivals and colleagues have quickly been jettisoned by clubs seeking instant success.
Wenger and Ferguson are the only managers in the top three divisions appointed to their jobs before the turn of the century.
Wenger has been in charge of Arsenal for 632 games, winning 365, drawing 156 and losing 111 with a win ratio of 57.75 per cent, British media reported.
Ferguson has an almost identical win ratio of 57.60 per cent. His 1,170 matches in charge of United have produced 674 wins, 280 draws and 216 defeats.