Definition of "backline"

Havertz oozed class on the ball, looking every inch the high-end addition, while City knew that they had to find a way past N’Golo Kanté before they got at Chelsea’s miserly backline, which absorbed the loss of Thiago Silva to injury on 38 minutes.

2021 May 29, David Hytner, “Chelsea win Champions League after Kai Havertz stuns Manchester City”, in The Guardian‎