Bayer Leverkusen overcame a 45-minute storm delay to beat fourth-division Grossaspach 4-0 in Erik Ten Hag's opening match as coach on Friday.
A hailstorm swept across the pitch in south-western Germany with the match scoreless after 15 minutes, delaying the game by three-quarters of an hour.
When play resumed with puddles across the field, Leverkusen striker Patrik Schick headed in the opener from an Amine Adli cross to give the visitors the lead after 32 minutes.
Grossaspach had several chances to equalise, taking advantage of a lack of Leverkusen fluidity in their first competitive game under the former Manchester United mentor.
Second-half goals from Arthur, Christian Kofane and Alex Grimaldo's penalty allowed the 2024 German Cup winners to overrun their opponents, booking a spot in the second round.
Ten Hag replaced former Leverkusen mentor Xabi Alonso in the summer.
Later on Friday, six-time winners Werder Bremen play away at last season's beaten finalists Arminia Bielefeld.