Wolfsburg finally got back to winning ways after seven fixtures without tasting victory by defeating Frankfurt 2-0 away on Saturday.
Casteels deserves the adulation of his team-mates for that clean sheet, as he made a huge eight saves on the day, frustrating the hosts who fired 17 shots on goal.
One save at the beginning, and one at the end, proved vital. Around eight minutes in he got down to his right to beat away a Goncalo Paciencia diving header, and then late on, with the score already at 2-0, he blocked a fizzing strike from Erik Durm.
Wolfsburg went down to 10 men a minute after the break, and with Frankfurt continually heaping on the pressure, he was forced to send 23 long balls forward.
As well as those aforementioned eight saves, he also made 16 interceptions on crosses into the box.