In the 48th minute, from a Reece James corner, defender Trevoh Chalobah rose highest to flick a header into the far corner, leaving goalkeeper David Raya helpless.

According to Sky Sports, this goal might have been invalid due to Enzo Fernandez's offside position, which appeared to impact Cristhian Mosquera's defensive ability.

Trevoh Chalobah's backward header opened the scoring in Chelsea's 1-1 draw with Arsenal at Stamford Bridge, London, England on 30/11. Photo: Sky Sports

When Chalobah touched the ball, Fernandez was behind the Arsenal defense and did not make direct contact with the ball. However, the Argentine midfielder was positioned precisely where Mosquera was retreating to clear the ball and may have screened or limited the Arsenal defender's ability to react.

According to the Laws of the Game, issued by IFAB, a player in an offside position is penalized if they interfere with play, interfere with an opponent, or gain an advantage by being in that position.

Fernandez appeared to be offside and limited Mosquera's defensive ability. Photo: Sky Sports

Fernandez's situation brought all three criteria into question. While Mosquera's arm was level with Fernandez, the law specifies that hands and arms are not considered in offside judgments. The determining point is the sleeve, and from the angle, Fernandez appeared to be higher than Mosquera.

This incident occurred amidst a series of controversial offside decisions in the Premier League. Previously, in Liverpool's 0-3 loss to Man City, defender Virgil van Dijk had a goal disallowed because Andy Robertson was deemed to have influenced the play despite not touching the ball.

Conversely, Nottingham Forest's goal by Murillo against Liverpool was allowed despite Dan Ndoye being in an offside position, on the grounds that he did not obstruct goalkeeper Alisson's view.

"Regarding the match between Chelsea and Arsenal, the question is whether the VAR team missed a crucial offside – which could directly affect this season's title race?", Sky Sports commented, adding that they had contacted PGMOL for an official response.

Van Dijk's disallowed goal in Liverpool's loss to Man City at Etihad Stadium, Manchester, United Kingdom, Premier League matchweek 11 on the evening of 9/11. Photo: Guardian

At Stamford Bridge on 30/11, Arsenal had a man advantage after Moises Caicedo received a red card in the 38th minute. However, they allowed Trevoh Chalobah to score early in the second half, and only a moment of brilliance from Mikel Merino secured a 1-1 draw.

Despite sharing points, Arsenal extended their unbeaten streak to 17 matches and are unbeaten in seven recent trips to Stamford Bridge, with three wins and four draws. Arteta's team remains at the top of the Premier League table with 30 points, five points ahead of second-placed Man City.

In the next round on 3/12, the "Gunners" return home to face Brentford, the 10th-placed club.

Hong Duy (according to Sky Sports)