For the first time in UFC history, a championship has changed hands based on a disqualification.In the first of three title fights at Saturday's UFC 259 pay-per-view, Petr Yan lost his bantamweight belt to Aljamain Sterling after landing an illegal knee in the fourth round.At the time of the foul, Sterling was clearly grounded following a failed takedown attempt. Under the rules of MMA, this means that no knee strikes are permitted. Referee Mark Smith warned Yan of Sterling's downed status at the time, but the Russian failed to heed the official's instructions.Yan hit Sterling with a stiff knee to the head at 4:29 of round four - and it was immediately obvious that the American challenger was in trouble. Sterling tried to get back up, but was soon back on the canvas, rolling around in pain.The ringside doctor immediately checked upon Sterling to determine whether he was in any position to continue. However, it quickly became obvious that the blow had caused some serious damage.Although he clearly wanted to continue, signs that Sterling was concussed were too powerful for the medic to ignore. Despite Sterling's pleas, the bout was thrown out.

Knee Strike DQ Videos

Disappointing Ending

Sterling becomes a UFC champion for the first time in his career, but was visibly distraught by the outcome. When awarded the title by Dana White, he almost immediately threw it to the floor - before collapsing with emotion.

Following the conclusion of the fight, it emerged that a member of Yan's team had actually instructed him to throw the knee, even though Sterling was in a downed position.

Not being a native English speaker, a language barrier could well have played a part in Yan's costly misjudgement. He was full of apologies after the bout - and will seemingly get an immediate chance to regain the gold as soon as Sterling is healthy and cleared to fight.

One of the most controversial endings in UFC history will be revisited sooner rather than later.