Chelsea will pursue Aymeric Laporte this summer to improve their defensive line.
Laporte was expected to join Manchester City last summer before he chose to remain with Athletic Bilbao. Pep Guardiola continues to have interest in Laporte.
By signing a new deal at San Mames, Laporte secured a buy-out clause of €65 million (£54.6m), which will increase to €70 million (£58.9 million) from the 2018-19 campaign onwards.