Costa is a notorious wind-up merchant on the pitch and has got opponents into trouble in the past with his expertise in the dark arts
But Mertesacker said: “We went to work on Diego Costa.
“Rob (Holding) was giving him a really hard time. I kept patting him on the back, being friendly, while Rob kept on talking to him. A good double act. It was very exciting to see how quickly things can turn.
“What was really important was that we kept on running with Costa, to make sure those long balls didn’t get to him.
“We were prepared for that. Especially when Fabregas came on, we were ready to run back to cut out those long balls over the top that he plays.
“You have to say it couldn’t have gone much better for us. The team’s performance was incredible. I don’t know how many would have expected that.”