The Spaniard had come under increasing pressure during a run that has seen the Merseyside club win just one of their last 11 Premier League matches and lose to Manchester United in the semi-finals of the FA Cup.

With Leicester City winning the title in a season where the English top-flight's established powers have all faltered, there is a deep sense of frustration among many Everton fans at Martinez's failure to get more out of a squad including rising England stars Ross Barkley and John Stones.

Last week's 3-1 defeat by Leicester was followed by Wednesday's even worse 3-0 loss away to strugglers Sunderland -- who spared themselves from relegation in the process of a comprehensive victory at the Stadium of Light.

Afterwards, Martinez insisted he was "100 percent" committed to remaining in charge of Liverpool-based Everton.

But Wednesday's result is believed to have been the final straw for new majority investor Farhad Moshiri, with Martinez, who joined Everton from Wigan in 2013, now set to be dismissed before Saturday's final game of the season at home to Norwich.

Sacking Martinez might also stave off a planned protest by supporters at Everton's scheduled Player of the Year dinner on Thursday.