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César Cielo currently holds the world record in the 50-metre freestyle, which he set in 2009 with a time of 20.91 seconds. The record was previously held by American swimmer Anthony Ervin, who set a time of 20.96 seconds in 2000. Cielo's record is the fastest time ever recorded in the 50-metre freestyle, and it is considered to be one of the most difficult world records to break.