By London correspondent Tony Hughes

Alexis Sanchez needs a rest, referees have to cut out Diego Costa’s unsavoury antics and other things we learned from Chelsea 2 Arsenal 0.

Sanchez looks exhausted after Copa America exertions

Sanchez has misplaced his mojo. No goals and not much in the way of penetration, Arsenal’s best player of last season looks exhausted after leading Chile to their Copa America triumph in the summer. Arsene Wenger promised to gradually ease the £32million man into this season but that has proved not to be the case. After coming off the bench in the team’s opening-day Premier League defeat to West Ham, he has started all six of their subsequent fixtures. Even for a player labelled as “hyperactive” by his manager, it has been a heavy workload. Wenger recognised that Sanchez was below par against Chelsea by substituting him in the second half as Arsenal chased an equaliser. It is time for him to be taken out of the firing line for a few games. Wenger has plenty of other options on the flanks and Sanchez will benefit from the rest.

Referees need to get to grips with Costa’s antics

Smart wind-up merchant? Or out-of-control bully boy? Opinion is generally split between those who support Chelsea and those who do not. Referees have generally turned a blind eye to Costa’s antics during his season-and-a-bit in the Premier League. His blatant provocation of opponents seems to be regarded as part of the game, with the worst outcome for the player tending to be a booking or a quiet word. This laissez-faire approach is shameful and giving Costa licence to get away with murder. Mike Dean handled Costa abysmally at Stamford Bridge. His roll of dishonour included slapping Laurent Koscielny’s face, chest-bumping the defender to the ground, scratching Gabriel’s neck and scything down Alex Oxlade-Chamberlain What more does he have to do to get sent-off? Referees need to wise up to the forward and show him his unsavoury behaviour will not be tolerated. A few timely red cards would surely force a re-think.

Anger management: Gabriel saw red after being provoked by Diego Costa

Anger management: Gabriel saw red after being provoked by Diego Costa

Gabriel is far from the finished article

To Wenger’s credit, he did not try and excuse Gabriel’s petulance in a considered appraisal of the game’s controversies. The 24-year-old got what he deserved for aiming at kick at Costa. It was petulant and unnecessary. He also showed great naivety in being drawn into his fellow Brazilian’s web of deceit and dark arts. Gabriel is a hugely promising centre-back who has impressed greatly over the last month. He is in the team on merit. But his stupidity in falling for Costa’s antics cost Arsenal dearly and showed he is not yet the finished article.

Zouma could be hard to dislodge from starting X1

Talking of young centre-backs, Kurt Zouma gave further confirmation of his immense potential as Chelsea kept their first Premier League clean sheet of the season. After being giving the nod to start ahead of John Terry, presumably with Theo Walcott’s electric pace a mitigating factor, the Frenchman responded impressively. He defended with intelligence and commitment, and popped up in the opposition box to head in the crucial first goal of the match. Zouma could be hard to dislodge from the team in the coming weeks.

Seeing red: Santi Cazorla was the second Arsenal player to be sent off

Seeing red: Santi Cazorla was the second Arsenal player to be sent off

Cazorla is not the central midfield answer

Against elite opponents, Santi Cazorla is not the answer in central midfield. Yes, he is more effective in the centre rather than pushed out wide. And, yes, he formed an admirable partnership with Francis Coquelin in the second half of last season. But it is hard to see a Coquelin-Cazorla partnership being the bedrock of a strong title challenge. Evidence of this was provided at Stamford Bridge as neither player completed the 90 minutes. Coquelin was substituted at half-time and the Spaniard was sent off after his awfully timed tackle on Cesc Fabregas provoked a second yellow card. It was poor game management from Cazorla. He is an intelligent player of touch and vision but he does not have the defensive instincts and mobility to protect the back line.