Arteta later said: "I was praying. It was a really emotional game. A great team to play against. 3-0 up you're in control and then an individual error happen that clicks something. We started to deal with the situation better, but they have the players to put a lot of courage forward.
"Last year as well we had to suffer in the second half to win the game. The team has another tool to grab which is the confidence that in the big games you have the ability to win it.
"When you win it's always the case. Last season we didn't against West Ham we didn't score a penalty and we conceded in the 91st minute and we didn't have it because we didn't win. The margins are so small. Don't get carried away with yourself."
On Havertz, he added: "He was sensational in every department today. He was ill before the match and still he put the performance that he put in. I thought he was unbelievable today."