Ange Postecoglou was sacked by Nottingham Forest 19 minutes after Chelsea's Premier League victory at Nottingham Forest's City Ground.
The 60-year-old leaves after only 39 days and eight winless games after replacing Nuno Espirito Santo last month.
Defender Josh Acheampong and winger Pedro Neto scored just after half-time, prompting chants of "you don't know what you are doing" from the home supporters after Postecoglou reacted by immediately bringing on Callum Hudson-Odoi, before captain Reece James sealed victory in a 3-0 win for Chelsea.
Forest owner Evangelos Marinakis left the directors' box after 66 minutes.
Postecoglou will bemoan Forest's failure to capitalise on a dominant first half, when striker Taiwo Awoniyi, making his first start since a serious abdominal injury left him in a coma last season, missed an early chance. Morgan Gibbs-White also missed two first-half chances.
Chelsea struggled with a makeshift midfield, missing the injured Cole Palmer and Enzo Fernandez, while Moises Caicedo started on the bench.
However, three half-time changes by manager Enzo Maresca, including the introduction of star midfielder Caicedo, helped turn the game.
Acheampong, 19, was unmarked when he headed home Neto's cross from close range four minutes after the interval. Neto curled a free-kick past Forest's wall and goalkeeper Matz Sels three minutes later.
James volleyed in a third after a poor Sels clearance and Chelsea defender Malo Gusto was sent off for a second yellow card in a hectic last few moments of the match.
Postecoglou was seen shaking his head minutes earlier after defender Neco Williams volleyed over when unmarked. Substitute striker Igor Jesus then hit the post and bar as poor finishing cost Forest.
Forest lost six and drew two of his eight matches in charge after replacing Nuno Espirito Santo in September.
BBC