Anthony Joshua has been savaged on social media after he posted this picture of himself praying in a mosque.
Some followers criticised him for appearing to support Islam and said they will in turn support his rival, Wladimir Klitschko, in their forthcoming fight.
Joshua has previously said that he is not religious but is interested in faith. The boxer, who won gold in the 2012 Olympic Games, received support from many Twitter users.
Some pointed out that Muhammad Ali, the most famous boxer of all time, was Muslim.