Midfielder Paul Hartley believes the new system, which has produced two victories, will stand the team in good stead for Champions League trips.
"There have been some good performances over the last few weeks," Hartley told celticfc.net.
"The different formation worked well against Feyenoord. We've used it in a few games now and the boys looked comfortable with the system.
"I'm sure it's given the manager something to think about for the season ahead.
"The shape was good and against certain opposition, especially in Europe, it could be really useful."