The former Chelsea winger had the distressing time of his career since moving to Arsenal last summer for free.
The 32-year old winger managed zero goals and five assists across 21 Premier League games.
He lost his place in the Gunners squad earlier this season but have managed to be back looking like himself on the pitch.
Willian told ESPN Brazil: “It really was a very difficult start, apart from that first game against Fulham, where I had a good performance, I managed to make a good game.
“Even after that game there were some games that we won, I even had a good game, but then we ended up getting a bad streak.
“I also got a bad streak and I think my worst professional time to date, since I went up at Corinthians and was sold to Ukraine, then I arrived at Chelsea.
“Without a doubt. This phase that passed now was the worst time that I think I lived as a professional.”
“Of course, when you live in a difficult moment, you get really upset and try to find solutions, a way to improve, try to help the team. That’s what I’ve been doing all this time, I never stopped training, to work, to dedicate myself as much as possible.
“It took a little while to leave, but lately in the last games I’ve been playing well again, standing out with assists, playing well. So I’m happy to be back to find my good football.”
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