Concerned Barry Ferguson has urged Gio van Bronckhorst to focus on the Premiership title race ahead of the blockbuster clash in Dortmund.
The Scottish champions face a mammoth task to see off the Bundesliga giants as they prepare for the Europa League first leg at the Westfalenstadion.
While it's a chance to earn a landmark result, Ibrox legend Ferguson insists the focus has to be on the title fight with Celtic.
He admits the Rangers players could run out of steam during the relentless fixture list, having experienced the same during the famous run to the UEFA Cup Final in 2008.
When asked on The Go Radio Football Show if he was concerned about the build-up of European games, he said: "Not from the first half of the season, where you get the break at Christmas.
"But after Christmas it does become a worry. I've been in the position myself, and it's tough playing Thursday, Sunday, Thursday, Sunday at some stage.
"Back in Walter Smith's team, it was probably the same 14 or 15 players he used throughout all those games.
"There comes a stage where you just burnout.
"It is tough on Rangers. Will he (Gio van Bronckhorst) make a few changes tomorrow, then make a few changes at the weekend? I think that is something he will need to look at.
"For me the bread and butter is the league. That's where the big pay cheque is at the end of the season.
"Europe is great, it can be great for the bank account, but I think Gio will look at the bigger picture and the league."
