Arsenal sent out a message to Liverpool with a 2-0 win over Manchester United on Wednesday night.And the Gunners utilised their incredible ability to score from corners to claim all three points at the Emirates with Jurrien Timber and William Saliba grabbing the goals.Corners from both sides, delivered with such venom that caused United defenders to revert to panic stations, led to the goals.Declan Rice’s delivery into the near-post was deftly tapped on by Timber to open the scores after the break.Jurrien Timber scored Arsenal’s opener after the breakReutersAnd it was Bukayo Saka’s far-post corner later on that doubled the lead, where Thomas Partey headed it back across goal where it hit Saliba and rolled in.It has been a reliable weapon for Arsenal over the past couple of years or so and United will feel aggrieved to have been the latest victim, considering that they had largely kept their opponents’ open-play shackled – but what have we learned?Ruben Amorim has a mighty task on his handsA relatively even first half gave way to one-way traffic after the break as Arsenal took control and United faltered.Amorim made some surprise calls ahead of kick-off including the decision to start Tyrell Malacia – his first Premier League start in 18 months.It did not last long, however, being roped off at half-time as the Red Devils struggled to break down the Gunners.But they were outclassed in all three areas of the pitch – defence, midfield and attack – with Declan Rice particularly looking imposing.JUST IN: FA make decision on Marc Guehi after defiant religious message on rainbow armbandGabriel is not Arsenal’s only weaponArsenal fans were disappointed to see that Gabriel was not deemed fit enough to start aggainst United.The Brazilian has been Mikel Arteta’s not-so-secret weapon from corners, scoring three from set-pieces this season.But in his absence, Timber was the chosen target this time – and he reaped his rewards when he nodded in Rice’s corner after the break.Timber was not the only one to benefit, as Saliba doubled the lead, though he was none the wiser as the ball came off his back to go over the line from Partey’s cut-back header.READ MORE: Man Utd internal discord as Adidas fume at U-turn on LGBTQ+ jacket plans when one player refusedWilliam Saliba doubled Arsenal’s lead from, you guessed it, a cornerReutersArsenal’s squad depthGabriel was not the only player missing for Arsenal on Wednesday with Ben White also out of action for the foreseeable future with Oleksandr Zinchenko coming in.Jakub Kiwior was the other defender to make up the back-four alongside William Saliba and Timber and they kept it watertight at the back.United have plenty of attacking woes and would have needed to be on their A-game to trouble the Gunners, which they were not.LATEST SPORT NEWS:Ruben Amorim was mortified to see his side concede twice from cornersReutersAmorim cannot replicate Jose MourinhoUnited’s record at the Emirates is abysmal, where they have not won for nearly seven years to the day when they won 3-1 in December 2017.On that occasion, Jose Mourinho was in charge of the Red Devils and had his side purring with early goals from Antonio Valencia and Jesse Lingard setting the tone.However, his compatriot Amorim, who has been linked to The Special One, could not do as his countryman had done on that occasion and land the three points at the Emirates.Several United managers have found it difficult to topple the Gunners including Ole Gunnar Solskjaer and Erik ten Hag, but Amorim will come again on January 11 when the two sides meet in the third round of the FA Cup.