The Brazilian gave what Arsenal fans hoped as a glimpse of what was to come for the experienced forward. But performances have scuppered ever since then - having struggled to register not a goal nor an assist since.
Since the impressive debut
With cameos even at centre-forward for Arsenal at the Etihad against Manchester City - Willian has struggled to make his mark in any recent games for The Gunners; especially when playing out on the right.
The Brazilian's best performance since opening day came in the last 20 minutes of a game against Sheffield United when he played in midfield as the number 10 - with a trio of Bukayo Saka, Pierre-Emerick Aubameyang and Nicolas Pepe in front.
Frankly, the experienced ex-Chelsea man's recent performances have been nothing short of atrocious. Chelsea fans were often quite critical of his inconsistent form - quoting that he would perform well in only 2 or 3 games in every 10 games.
The Brazilian needs to start to show up more as fans outrage about his continued starting spot in The Gunners XI. Three assists in all competitions and yet to get off the mark for the red side of London is simply not good enough for a player of his calibre.
As an Arsenal fan; I think it is time to stop obstructing Nicolas Pepe's minutes on the right of Arsenal's front three and either deploy Willian on the left with the ability for him to cut inside onto his stronger right foot with Saka at number 10.
Preferably, however, Arteta should try the newly-signed experienced winger at number 10 - like he was deployed against Sheffield United with the same front three in front of him.
For me; the ex-Chelsea man is a combination-player who thrives when he is allowed the space to turn and run at an opposition defence with the option to link play with his teammates.
He is not so good as a right-winger when he is forced wide onto his albeit strong foot; he is not so good at beating a defender 1v1 thus struggles to create any meaningful chances from these positions.
The hierarchy at Arsenal, including Edu Gaspar, who is said to have been infatuated with the Brazilian ever since his days at Corinthians all the way back in 2006, would prefer him in the middle, rather than a wide man; they see him as playing the role of a midfield creator filling the half-spaces behind opposing midfields.
If Mikel Arteta is determined to start Willian in every Premier League game this season, he at least needs to get him playing in situations and positions that most suit his style of play.
But also in a position which does not hinder the team's ability to play their other talented forward talents.