Sunderland had not started a game of football with a back five this season. Enzo Maresca knows this, because in preparation for their visit to take on his side at the weekend, he watched back all nine fixtures they had played in all competitions in 2025-26.
Sure, they had switched to that system for the last 10 minutes when they had the odd lead to defend, but never from the beginning. Then, they turned up at Stamford Bridge.