Dortmund could stray from their tried and tested 3-4-2-1 formation this midweek when they take on Lazio in the Champions League.
With defenders Marcel Schmelzer, Nico Schulz, and Dan-Axel Zagadou already out injured prior to the weekend's win over Hoffenheim, Lukasz Piszczek came into the back three to partner Emre Can and Mats Hummels.
However, midway through the first half the Poland international had to be withdrawn due to injury, too, with Thomas Delaney slotting into the three-man defence.
Dortmund: Squad, FC Ratings, Matches, Formations
2020/21 Champions League: Groups, Matches, Team Stats, Player Stats
Rather than play two essential defensive midfielders in Delaney and Can in the back three against Lazio, Favre could opt to change to four at the back.
That would see Thomas Meunier drop in to right back with either Raphael Guerreiro or Felix Passlack dropping deep at the other side.
Erling Haaland was rested against Hoffenheim, but expect Dortmund's star striker to return to lead the line against the Serie A side.
Marco Reus came off the bench to score the winner on Saturday, which could be enough for him to earn a start in Europe, with Jadon Sancho likely to be deployed in behind Haaland, too.
Dortmund starting XI versus Lazio
Jadon Sancho 
Marco Reus 
Erling Haaland 
Dortmund 
Lazio 
