Aug 12 (Reuters) - Former world heavyweight champion boxer David Haye will return to the ring after a three-year absence to fight Joe Fournier next month, the 40-year-old Briton said on Thursday. Haye, who won the world heavyweight title in 2009 when he beat Nikolai Valuev, retired in 2018 with a 28-4 record following a re-match defeat by fellow Englishman Tony Bellew. He will face Fournier, an entrepreneur who moved into the nightclub industry before making his professional boxing debut in 2015. Fournier usually competes in the light-heavyweight division and has a 9-0 record. "This isn"t a comeback, this is about teaching there are levels in boxing. One must stay in their lane or risk getting flattened," said Haye, who is also a former world cruiserweight champion. "I was the heavyweight champion of the world just 10 years ago. I"m only 40. Joe is delusional. Champions are born not bought." The pair have agreed to an eight-round heavyweight fight on Sept. 11 at the Staples Center in Los Angeles. The bout will take place on the undercard of Oscar De La Hoya"s comeback at the age of 48 against former UFC champion Vitor Belfort.