Greece international goalkeeper Dimi Konstantopoulos has extended his contract with Middlesbrough, although terms are undisclosed.
Konstantopoulos, 36, has emerged as Boro's first-choice keeper this season, despite the permanent arrival of Tomas Mejias from Real Madrid.
He currently has 14 clean sheets in 29 league and cup games this term.
"It's great news for everyone. Dimi is the kind of player you want in your squad," Boro boss Aitor Karanka said.
"He was the third goalkeeper in the squad when we came here and now he is number one. He has done really well.
"He brings experience to the dressing room and he is a very important member of our squad on and off the pitch."
Boro currently occupy the second automatic promotion place in the Championship, two points behind leaders Derby.