Another illegal knee mars a UFC match and an MMA analyst said it is a fighter's responsibility to know rules

• A UFC match between Eryk Anders and Darren Stewart was ruled a no contest Saturday.
• Anders hit Stewart with an illegal knee but it was deemed accidental.
• It happened one week after another fighter.

Another illegal knee has marred a UFC match and an MMA analyst said it is a fighter's responsibility to know the rules.

A middleweight fight between Eryk Anders and Darren Stewart opened the main card of the behind-closed-doors UFC Fight Night 187 event at the Apex in Las Vegas.

The 185-pound bout was abandoned when the British fighter Stewart absorbed a knee strike while he was in a grounded position.

Anders was more active than Stewart, with 58 of 79 strike attempts landing for a 73% accuracy rate in the first round, compared to Stewart's return of 21 from 51 strikes (41%).

Stewart's fast, powerful strikes seemingly inspired Anders to move away from stand-up exchanges by seeking takedowns, and he succeeded with three of his seven attempts, according to UFC statistics.

Anders shellacked Stewart by the fence towards the end of the round with a series of shots that were so unrelenting, Stewart eventually dropped the floor. Anders then threw the illegal knee.

It is the second week in a row when an illegal knee has brought an early finish to a fight, and the MMA commentator and former UFC title challenger Dan Hardy said combat athletes should know when opponents are in grounded positions.

"Just to clarify, a fighter with one knee down is always considered a grounded opponent," Hardy tweeted.

"It is the fighter's responsibility to know this rule," he said.

In a further statement, Hardy added: "A grounded fighter is defined as: Any part of the body, other [than the] sole of the feet touching the fighting area floor.

"To be grounded, the palm of one hand (a flat palm) must be down, and/or any other body part must be touching the fighting area floor.

"A single knee, arm (not fingers) makes the fighter grounded without having to have any other body part in touch with the fighting area floor. At this time, kicks or knees to the head will not be allowed."

The no-contest follows an illegal knee last week that resulted in a disqualification and a UFC championship changing hands.

American fighter Aljamain Sterling won the bout when his Petr Yan threw an illegal knee midway through their UFC 259 bantamweight title fight.

Sterling was on the canvas after a failed takedown attempt. Despite a warning from the referee, Mark Smith, Yan threw his knee at Sterling.

The 31-year-old was deemed unfit to continue and so he was declared the winner, Insider previously reported.

Why Yan's knee was different to Anders'

Marc Ratner, who is in charge of regulatory affairs at the UFC, addressed the press to explain that the difference between last week's disqualification, and this weekend's no contest, is because of intent.

Yan intended to throw the illegal knee against Sterling while the latest incident involving Anders and Stewart was accidental, the regulator said.

"This week, in the referee's opinion, he ruled it accidental," said Ratner in a statement recorded by The Schmozone podcast.

"By the rules, if a fight doesn't go two complete rounds it becomes a no contest/ no decision.

"If the fight had gone into the third round, the judges would have scored that round, the fight couldn't have gone on, and it would have been a technical decision [for whoever had won on the judges' cards]."