Lee Cattermole has committed his long-term future to Sunderland by signing a five-year contract extension.
Cattermole, 27, who had 12 months remaining on his existing deal, has now been tied up until the summer of 2021.
Head coach Dick Advocaat told the club's official website: "Lee is the controller of the side. He is a motivator, a leader and central to the success of our team. To know that he will be with us for many years to come is very important to the club."
- Sunderland AFC (@SunderlandAFC) July 2, 2015
Sunderland's sporting director Lee Congerton added: "Lee is a hugely important part of our team, both on and off the field.
"He has 10 years of experience playing in the Premier League, which is incredible when you consider he is still only 27 years old, and we are delighted that he has committed his long-term future to Sunderland."
The midfielder received 14 yellow cards last season, which is a joint-record for one player in a Premier League season.
Cattermole's deal follows Advocaat securing his first signing on Wednesday evening, with Liverpool defender Sebastian Coates completing a permanent switch to the Stadium of Light following his loan spell last season.