Atletico Madrid should give Jan Oblak a "blank cheque" to make sure that the reported Arsenal, Chelsea and Liverpool target remains at the club this summer, according to his teammate Koke.
Oblak, 25, is widely seen as one of the top goalkeepers, with the €16 million signing from Benfica in summer 2014 now rated at €100m and reportedly being pursued by many of Europe's richest clubs.
The Slovenia international said while on international duty last month that no progress had been made on a contract extension at Atletico, which meant he is considering all his options ahead of the 2018-19 season.
He proved his worth to Atletico again on Thursday as a string of top saves -- aside from one important mistake -- allowed his club to qualify for the Europa League semifinals 2-1 on aggregate despite a 1-0 defeat at Sporting Lisbon.
"Jan has got us used to him playing great games," Koke told "El Larguero" radio show. "If I was in charge of this club I would give him a blank cheque [to stay]."
Saul Niguez also praised Oblak as the world's best, adding that it would better if he was not given so many opportunities to show off his skills following another outstanding display in last weekend's 1-1 La Liga derbi draw against Real Madrid.
"[Oblak] is the best keeper in the world. He keeps improving and helping us," Saul said after the game. "We hope he keeps going like this, but with less work to do."
The game also brought further worries for coach Diego Simeone with centre-forward Diego Costa injuring a thigh and defender Lucas Hernandez leaving the pitch after getting hit in the face.
The two players were to undergo more tests in Madrid on Friday but are unlikely to feature at home to Levante on Sunday at the Wanda Metropolitano.
That would leave Simeone with just 13 available outfield players, with left-back Filipe Luis out for the season with a broken leg and Yannick Carrasco, Nico Gaitan and Augusto Fernandez all having been sold to Chinese clubs earlier this year.