Bayern Munich eased into the German Cup third round on Tuesday by crushing second division Oberhausen 5-0.
Playmaker Franck Ribery and striker Miroslav Klose, both trying to get matches under their belts following leg injuries, started while Italian striker Luca Toni played for the first time this season after injury, coming on as a substitute.
"Ahead of the busy week I made many changes to keep our first team players fit because we have an important (Bundesliga) match against Hamburg on Saturday," van Gaal, who rested several key players including Dutchman Arjen Robben and Bastian Schweinsteiger, told reporters.
The hosts needed an Oberhausen own goal to take the lead after 32 minutes before Mario Gomez sent them into halftime with a two-goal cushion.
A brace from defender Daniel van Buyten, scoring for the third straight match, and a Thomas Mueller goal, set up by Toni, completed the rout.
Hoffenheim edged past Nuremberg 1-0 thanks to a Per Nilsson header, but fellow Bundesliga club Borussia Moenchengladbach were eliminated after second-division Duisburg's substitute Kristoffer Andersen scored a stoppage-time winner for a 1-0 victory.
Schalke also advanced, downing VfL Bochum 3-0.
