Stuttgart had been fighting with Hoffenheim over Sauer's signature, which the 20-year-old will put under a contract valid until 2031.
Feyenoord are set to receive €12.5 million for Sauer, with the fee possibly rising to €15 million through bonuses. A sell-on clause has been included in Sauer's contract, according to Voetbal International
Leo Sauer, an 11-time Slovakia international, joined Feyenoord at age 17 in 2023 and scored on his Eredivisie debut against Sparta Rotterdam. Sauer joined fellow Eredivisie side NAC Breda on loan during the 2024/25 season, scoring 7 goals in 32 appearances.
Upon his return in Rotterdam, manager Robin van Persie never guaranteed anyone except striker Ayase Ueda a starting spot in Feyenoord's attack. Along with two hamstring injuries, Sauer was limited to 20 Eredivisie appearances during the 2025/26 season, during which he scored 3 goals.
In total, Sauer played 44 games for Feyenoord, scoring 6 goals and providing 5 assists along the way. Sauer was under contract at Feyenoord until 2028.