But the assignment, at Lewisham Theatre in south London, threatens to be McKenzie's last world title attempt after previous spells as the International Boxing Federation flyweight and WBO bantamweight champion.
Benavides, a 28-year-old southpaw, is an overwhelming favourite after losing just once in 34 professional fights. 'This is the toughest fight I've ever had,' said McKenzie, who is a year older than his Texan opponent. 'Benavides is a good champion and just about everybody puts him as No 1 among the current title-holders.'
McKenzie's task appears all the tougher as his last fight was a one- round defeat by Puerto Rico's Rafael Del Valle in May.