Brighton have announced the signing of Austria left-back Markus Suttner from Ingolstadt.
Premier League club Stoke City and 2. Bundesliga side St. Pauli have agreed a "long-term cooperation."
Second-tier club, based in the vibrant Reeperbahn area of the port city, have established a reputation for having left-wing ideals in recent decades.
Darmstadt completed the signing of United States youngster McKinze Gaines from Wolfsburg on Thursday.
Reconstruction work, which is due to begin in 2019, will mean the stadium has a standing capacity of 28,692.
Schalke sacked coach Markus Weinzierl one season into his three-year deal on Friday and appointed Dominico Tedesco in his place.