Sanchez, the league joint-top scorer with 17, was left on the bench until halftime — by which time a rampant Liverpool side was 2-0 ahead thanks to goals from Roberto Firmino and Sadio Mane.
Arsenal was much improved with Sanchez on the field and he set up Danny Welbeck's goal in the 57th minute with a pass through the heart of Liverpool's defence, but Liverpool sealed victory in stoppage time through Georginio Wijnaldum's breakaway goal.
James Olley was at Anfield to assess Arsenal's performance...
Pressure intensifies on Wenger – again
The last remaining irrefutable argument Arsene Wenger cites in times of crisis is Arsenal’s unbroken qualification for the top four during his tenure.
That record is in jeopardy after falling to fifth place after another flawed performance at Anfield, with the only consolation being that Manchester United’s failure to beat Bournemouth earlier in the day ensured they did not drop further.
There are still 12 games remaining and only a two-point deficit to overcome but a small fan protest calling for Wenger to turn down a new contract and walk away was already planned prior to the Bayern Munich game. There may be a few more getting involved now.
Arsenal fail in a big game – again
The script is well-read. Arsenal fail to start with the requisite intensity and fall behind early, chasing their tails thereafter.
They actually started this game reasonably well – passing the ball well enough to try and take the sting out of it – but fell behind inside 10 minutes once Liverpool created their first clear opportunity.
Arsenal have now won just three of their last 24 Premier League matches away at top six opposition – that record is a damning indictment of Wenger’s ability to build a team capable of competing for the title.
Their second half improvement restored a modicum of respectability but they had already given themselves a mountain to climb with another dreadful start.
Sanchez gamble backfires
Arsenal had played down Mesut Ozil’s illness all week so his absence was something of a surprise but in any case, it was completely eclipsed by Wenger’s decision to drop Alexis Sanchez.
Wenger justified the decision to start Olivier Giroud with a need to go more direct –presumably in order to beat Liverpool’s ‘gegenpressing’ – but to leave out Sanchez from the start in a game of this magnitude felt like a statement to a player yet to commit his future to the club.
When asked about Sanchez’s feelings after Arsenal’s heavy defeat to Bayern Munich, Wenger made a point of noting that the team played badly and “Sanchez was part of that”.
They played appallingly without him here and it took only 12 minutes after his half-time introduction to make an impact, laying on Danny Welbeck’s reply for the visitors.
No Ozil but still no intensity
Ozil’s omission was enforced but some viewed it as a blessing in disguise given a series of underwhelming performances in recent weeks.
The German international’s agent claimed Ozil had been made a scapegoat for Arsenal’s disappointing results and he will point to their first-half showing here as evidence they display no greater conviction in his absence.
Alex Iwobi assumed an approximation of Ozil’s number ten role but it was noticeable that he had been instructed to drop deep when Arsenal did not have the ball as the visitors assumed a 4-5-1/4-3-3 shape to help stifle Liverpool on the ball. Its fair to say it didn’t pan out as planned.
Welbeck is ready to play a more significant role
One of the benefits of Arsenal’s 12-day hiatus was the opportunity to give Danny Welbeck two matches at Under-23 level, against Leicester and Chelsea.
He played 69 minutes in the first before completing the second and that boost to his match fitness was enough to earn his first League start since May 2016.
His goal gave Arsenal renewed hope in the second half and – once Sanchez was included to inject some purpose into their attacking play – Welbeck enhanced his case for greater involvement in the challenges ahead.
The fans’ view was clear enough: Wenger decision to replace Welbeck with Theo Walcott for the final 16 minutes was booed by the travelling support.