Steve McNamara has left his role as Catalans Dragons head coach with immediate effect, with Joel Tomkins to take temporary charge.
The French club have won just five of 11 Betfred Super League matches this season and were thrashed 40-0 by St Helens last time out.
Assistant coach Joel Tomkins - brother of player Sam - has stepped in on a caretaker basis and will lead the team in Saturday's match against Wigan in Perpignan.
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McNamara has been Super League's longest-serving head coach, having taken charge of Catalans in 2017 and saved them from relegation in the Million Pound Game.
Under McNamara, the club prospered, winning the Challenge Cup for the first time in 2018 and also reaching Super League Grand Finals in 2021 and 2023.
But they have struggled during the current campaign and their heavy defeat to Saints was preceded by a thumping Challenge Cup loss to Hull KR in York.