3. Demetrious Johnson vs. Ian McCall
Flyweight king Demetrious "Mighty Mouse" Johnson's ascent to the top started in 2012 at a UFC on FX event in Sydney, New South Wales, Australia. This was the UFC's 200th event and featured a welterweight main event between Thiago Alves and Martin Kampmann. The UFC was just introducing the flyweight division and held a tournament to determine the inaugural champion.
Johnson was just coming off a loss to bantamweight champion Dominick Cruz and was moving to the new division, sharing the first-ever flyweight bout in UFC history with Ian "Uncle Creepy" McCall. McCall was a former bantamweight himself who was on a modest four-fight win streak.
McCall scored the initial takedowns but Johnson was the better striker, often being too quick and even stunning McCall toward the end of the first round. The second round stayed on the feet, as Johnson was able to thwart McCall's takedowns and land more significant strikes. McCall was able to get Johnson back to the canvas, securing his back, landing repeated strikes and even getting full mount position to end the third and final round, but Johnson was able to survive.
McCall would land more strikes and complete more takedowns, though Johnson landed the more significant strikes. When the scorecards were originally read, Johnson had won by majority decision. However, later in the evening while reviewing the scorecards, they caught an error, and the bout was declared a majority decision, with only one judge giving the fight to Johnson. Since the tournament should have resulted in a sudden death fourth round, the fight was rescheduled three months later and Johnson would go on to win by unanimous decision.
Johnson wouldn't lose a fight until five years later but would give us many incredible performances through the years as flyweight champion. McCall would go 2-3 from there on out, finishing out his career with RIZIN and retiring in 2018 after countless injuries. This fight was the first glimpse at how fun flyweight fights could be.