Schalke coach Markus Weinzierl has praised Tottenham loanee Nabil Bentaleb, but did not confirm they have already triggered an option to buy.
Badstuber received a rapturous reception when he came on to replace fellow Germany international Mats Hummels.
Borussia Dortmund midfielder Mario Gotze told reporters that his side's narrow defeat of Union Berlin did not go according to script on Wednesday.
Carlo Ancelotti praised predecessor Pep Guardiola for the Bayern Munich side he inherited as the German Cup holders moved into the DFB Pokal last 16.
Roger Schmidt is an undeniable asset as manager but Bayer Leverkusen's dismal form and Schmidt's stubbornness are causing problems.
After joining Bayern at the age of 10 in 2000, local boy Muller, now 27, made his first-team breakthrough during Van Gaal's spell in charge.