The Montreal Impact fired head coach John Limniatis on Thursday, one day after the team's 1-0 loss to Toronto FC.
The United Soccer Leagues team has named assistant coach Marc Dos Santos as interim head coach.
Limniatis's dismissal comes after the Impact were held winless in their first four games of USL Division One action, with a record of 0-3-1.
"After having analyzed the situation over the last few months, we have realized that the team was not playing to its level and that the positive results were not there," Impact technical director Nick De Santis said in a news release.
"The message was no longer getting through in the locker room. John will nevertheless remain in the Impact family, and he continues to be one of our great team builders."
The 41-year-old Limniatis, who was named head coach June 10, 2008, led Montreal to the CONCACAF Champions League quarter-finals and to the semifinals of the USL series in his first year with the team.
A former midfielder, he won 44 caps for Canada.
Dos Santos has been assistant coach of the Impact since June 2008. He becomes the eighth head coach in the team's history.
Dos Santos served as head coach of the reserve team, the Trois-Rivières Attak, in 2007 and 2008 and also took training internships with three first division clubs in Portugal.
"It's an honour for me to become interim head coach for the Impact," he said. "I am ready today to take on these new responsibilities. It's a great challenge in my coaching career, and it's a mandate in which I will invest myself fully ... I will do everything I can for the team to be successful again."
Dos Santos's coaching staff will consist of three assistant coaches: Andrea Di Pietrantonio, who held the same function last season; Mauro Biello, who becomes player-coach; and Youssef Dahha, who will remain goalie coach.
Dos Santos will coach his first game Friday when the Impact face the Charleston Battery.