Pietersen was famously sacked by the England and Wales Cricket Board following the Ashes whitewash 13 months ago.
Since then the South-African born batsmen has openly criticised his former team-mates and the ECB despite insisting he would still love to play for his adopted country.
England play Australia on Saturday hoping to lift the 50-over World Cup trophy for the first time.
Since reaching the final in 1992, England have one of the worst records out of all the leading nations. They have won only 16 matches, which is better only than Bangladesh and Zimbabwe.
But Pietersen, England???s leading World Cup scorer with 575 runs, has surprisingly backed his former team to surprise everyone and win the tournament as long as they play with freedom.
“I really do believe they have an outside chance of winning this World Cup,” Pietersen told the Daily Telegraph.
“They can play with freedom because nobody really expects them to win the tournament and this should be reflected in positivity throughout their batting.
“England have struggled in World Cups for 20 years because we have played directly after an Ashes and have been mentally shot. There are no excuses this time.”