Bayer Leverkusen have signed a new contract with defender Thanos Petsos until June 2014.
The 19-year-old is currently on loan at fellow Bundesliga outfit Kaiserslautern and that agreement has also been extended, with the move now until next summer.
Petsos joined Kaiserslautern on loan at the start of the season and the agreement does not involve any option for a permanent transfer.
Kaiserslautern manager Marco Kurz told Deutsche Presseagentur: "Thanos Petsos has made good progress this season.
"We feel his development is not yet finished. He is young, he is versatile and I am delighted we are able to further rely on him as a player."
The extended loan is a latest boost to Kaiserslautern, who earlier in April signed a new three-year contract with full-back Florian Dick and confirmed that Duisburg midfielder Olcay Sahan will arrive on a Bosman transfer this summer.
In contrast, Bayer Leverkusen look set to lose players at the end of the season, with defender Arturo Vidal revealing that he would be interested in following manager Jupp Heynckes to Bayern Munich.
"It would be spectacular to play in Munich under Jupp Heynckes," he told Bild. "I really want to play for Bayern."