Welcome to The Radar, a Sky Sports column in which Nick Wright uses data and opinion to shed light on Premier League stories. This week: Arsenal's defence still getting stronger, Rogers making instant Chelsea impact, Hull's unsung hero in defence, and a player to watch.

Sunday's game at the Emirates Stadium pits the Premier League's best defence against its best attack. Arsenal are yet to concede, while Chelsea have top-scored with seven in two games. Hull have also kept back-to-back clean sheets, but needed goalkeeper Konstantinos Tzolakis, while Arsenal's David Raya has been a bystander.

Since the start of last term, Arsenal have allowed under 0.50 expected goals in 20 out of 40 games. No other side gets close, with Liverpool next on eight. The absence of William Saliba and Jurrien Timber has barely registered, with Cristhian Mosquera deputising alongside Gabriel and Ben White at right-back. Bruno Guimaraes has been eased in.

The key lies in Mikel Arteta's tactical foundations. The back four of White, Mosquera, Gabriel and Riccardo Calafiori had never started together before this season. Arsenal's solidity provides optimism as they face their toughest test against free-scoring Chelsea.