Every fighter has their day.
As fighters age and new fighters develop, techniques evolve to break through the traditional defenses of particular disciplines.
With the skill level in combat sports being as high as it has ever been, fighters are closing the ability gap to the top of their divisions, and we begin to see vulnerabilities from fighters.
Whether it was a simple mistake, or exploit of a fighters' tendencies, we look at 5 notable combat sports athletes who have suffered a knockdown in 2018.
Claressa Shields
Two-Time Olympic gold medalist and WBC/WBA/IBF female middleweight champion Claressa Shields continues her dominant rise in boxing, becoming a two-division world champion in 2018.
However, Shields' career has not been without a scare.
In the main event of a ShoBox card in June 2018, Costa Rican WBA/WBO female super welterweight champion Hanna Gabriels moved up a weight class to face Shields.
In the closing minute of the first round after utilizing her movement, Gabriels grazed Shields with an uppercut-hook combo dropping 'T-Rex' to the canvas for the first time in her career.
Shields would eventually battle back and cruise to a unanimous decision victory to retain her titles.
Vasyl Lomachenko
Pound-for-pound number-one boxer Vasyl Lomachenko has had the spotlight on him since prior to his professional debut in 2013.
The three-division titlist, and current WBA/WBO lightweight champion had a notable amateur career going 396-1, plus winning consecutive Olympic gold medals in 2008 and 2012.
'Hi-Tech' would move up a weight class to face WBA lightweight champion Jorge Linares at a Top Rank on ESPN card in May 2018.
In the sixth round after a fairly even bout, Linares would catch Lomachenko walking in with a cross, dropping the Ukranian.
Lomachenko would eventually battle back and stop Linares with a body shot in the tenth.
James Gallagher
Bellator rising star James Gallagher made waves for the Scott Coker-led promotion since debuting for them in 2016.
The SBG Ireland product seemed to be following the footsteps of teammate Conor McGregor with his brash, outspoken personality.
After going 4-0 in the promotion, Gallagher was matched up against CFFC bantamweight champion Ricky Bandejas at Bellator 204. Before the fight, 'The Strabanimal' would attempt to get into Bandejas face to try to intimidate the fighter.
Midway through the first round, Bandejas would connect a punch on Gallagher, dropping the Irishman. Bandejas would follow up with a side kick and punches to knockout Gallagher, giving him the first loss of his career.
Cris Cyborg
Since stopping women's MMA pioneer Gina Carano in 2009, Cris Cyborg has always been at the top of the women's pound-for-pound list in the sport.
Since then, Cyborg had rattled off 12 victories (with one no contest, a 16-second stoppage of Hiroko Yamanaka which was overturned due to a positive drug test), 11 of them being finishes.
At UFC 232, Cyborg would attempt to defend her UFC women's featherweight title against heavy-handed women's bantamweight champion Amanda Nunes.
In previous fights, Cyborg would usually walk down fighters with her power. Unfortunately in this case, with a fighter packing as much power as Nunes, Cyborg's plan would backfire.
Just 30 seconds in after a wild exchange, Nunes would catch a charging Cyborg with a hook dropping the former featherweight champion to her knees. Within the next 15 seconds, Cyborg would touch the canvas three more times. Finally, with a rocked Cyborg backed up, swinging wildly against the cage, 'The Lioness' would put Cyborg down for the final time.
Conor McGregor
After the UFC 223 bus attack, the UFC promotional machine was all in on setting up a grudge match between Khabib Nurmagomedov and Conor McGregor.
Nurmagomedov and McGregor would be feuding for years leading up to their bout at UFC 229.
In the first round of their bout, 'The Eagle' would nullify McGregor's striking prowess by taking him down, in an attempt to slow the Irishman down and wear him out.
Early in the second round, Nurmagomedov would catch McGregor with an overhand right, dropping McGregor for the first time in the Octagon.
Nurmagomedov would eventually submit McGregor in the fourth round to retain his UFC lightweight title.