Winning the league championship used to be the ultimate achievement for any manager and make him bombproof for many years to come. That's not the case today. Incredibly, the last four mangers to have won the Premier League have all left their jobs by the following year – three sacked and one retired. And on the latest evidence, it will be no surprise if Manuel Pellegrini becomes number five this summer. A dejected Manuel Pellegrini following Manchester City's 2-1 defeat to Crystal Palace on Monday night . Pellegrini guided City to their second Premier League title in three seasons back in May . But Pellegrini's City side were humbled at Selhurst Park on Monday to kill off any remaining title hopes . City sit fourth after the defeat, nine points adrift of leaders Chelsea, who retain a game in hand . WIN THE LEAGUE..AND THEN OUT . JOSE MOURINHO (CHELSEA) Won Premier League in 2006; sacked 2007 . Jose Mourinho ended Chelsea's 50-year wait to be champions by winning the Premier League in his first season 2004/05, and then retained the trophy the following season. But as his reputation soared, his relationship with owner Roman Abramovich soured and he left in September 2007 despite having three years left on his contract. Despite domestic success, Abramovich craved the Champions League and had become frustrated with the team's defensive style. For his part, Mourinho felt belittled by having players signed on Abramovich's say-so, most notably Andriy Shevchenko who was a declining force. Mourinho celebrates winning back-to-back Premier League titles with Chelsea in 2006 . Mourinho departed Stamford Bridge the following year, despite having three years left on his contract . CARLO ANCELOTTI (CHELSEA) Won PL in 2010; sacked 2011 . Carlo Ancelotti led Chelsea to their first league and FA Cup Double in his first season, scoring a record number of goals that still stands today. However, he failed to win a trophy in his second season and that was enough for Abramovich to pull the trigger despite finishing second in the table. Ancelotti knew the game was up as he puffed on a cigarette and chatted to David Moyes after Chelsea had lost the final game of the season 1-0 at Everton. The Italian bounced back to win the Champions League with Real Madrid last season and will be among the contenders for the City job should Pellegrini leave. Carlo Ancelotti celebrates with the Premier League trophy after Chelsea secured the title in 2010 . Ancelotti departed Stamford Bridge a year later after failing to win silverware in his second season . ROBERTO MANCINI (MANCHESTER CITY) Won PL in 2012; sacked 2013 . Mancini ended City's 44-year wait for the league title when Sergio Aguero scored against QPR on the final minute of the final day of the season. Yet his controversial approach led to him falling out with Carlos Tevez and Mario Balotelli, and criticising Adam Johnson and Joe Hart, and when City failed to win a trophy the following season and failed in the Champions League, the Italian was out. His demise was widely reported on the morning of the FA Cup Final against Wigan Athletic. City fans chanted Mancini's name but they lost the final and he was dismissed the following week. Roberto Mancini celebrates with the Premier League trophy as Man City win the league in 2012 . Mancini waves goodbye after being sacked by Manchester City 12 months after the title win . SIR ALEX FERGUSON (MANCHESTER UNITED) Won PL in 2013; retired in 2013 . The only one of the managers who left on his own terms. Ferguson won a record 13th title and walked away into the sunset after the final game of the season, a remarkable 5-5 draw at West Brom. The United boss said later he had wanted to retire the previous season but City's title win persuaded him to carry on for another year and wrestle the trophy back – which he did. Ferguson helped pick David Moyes as his successor but he grew disillusioned with his fellow Scot after Moyes got rid of his assistant Mike Phelan and built a team around Wayne Rooney. Sir Alex Ferguson led Manchester United to their 13th Premier League title in 2013 before retiring . Ferguson salutes the fans after his final game in charge at United -  a 5-5 draw with West Brom in 2013 . MANUEL PELLEGRINI (MANCHESTER CITY) Won PL in 2014, ??? The Chilean followed Mourinho and Ancelotti in winning the Premier League in his first season and also lifted the Capital One Cup as Sergio Aguero and Yaya Toure in particular shone. But this season has been a major disappointment. City crashed out of the Capital One Cup, FA Cup and Champions League early and currently stand fourth in the Premier League. The knives are out.
Pellegrini is feeling the heat after Man City's 2-1 defeat to Crystal Palace .
The result left Man City nine points behind Chelsea in Premier League .
The last four managers to win title have left their posts soon after .
Jose Mourinho's first spell at Chelsea abruptly ended in 2007 .
Carlo Ancelotti suffered similar fate year after title success .
Roberto Mancini was shown door by City 12 months after first league title .
Sir Alex Ferguson retired after winning a 13th Premier League at United .
CLICK HERE for all the latest Manchester City news .