Even former-Borussia Dortmund coach Jurgen Klopp admits he has split loyalty for Saturday's hotly anticipated Ruhr Derby with both Schalke and arch-rivals Dortmund capable of going top of the Bundesliga.

The current Liverpool boss led Dortmund to back-to-back Bundesliga titles in 2011 and 2012, yet is torn over this weekend's match in Gelsenkirchen with close friend David Wagner now head coach of the hosts.

"This is the craziest situation in my life," Klopp admitted recently at an event in Dortmund.

"I am 100 percent black-and-yellow (for Dortmund), but now my best friend is the Schalke coach.

"I still don't know what to make of that."

Wagner, 48, a former Schalke player, fully understands the significance of the fixture having spent four years coaching Dortmund's reserves, working alongside Klopp, before steering Huddersfield Town to the Premier League, then returning to Germany to take charge of the Royal Blues this season.

"At Dortmund, they called me 'Schalker' for at least the first six months. I know what the derby means to everyone," Wagner admitted with a grin.

Dortmund expect to have playmaker and captain Marco Reus, who hit the winner in last Saturday's 1-0 victory over leaders Borussia Moenchengladbach, back from illness, but striker Paco Alcacer remains sidelined by a calf injury.

Either club could potentially go above table-topping Moenchengladbach with fourth-placed Dortmund just a point behind and Schalke, in seventh spot, trailing the leaders by two points.

Honours were even in last season's explosive derbies.

England winger Jadon Sancho, who was dropped for last weekend's victory over Gladbach after returning late from international duty, scored the winner as Dortmund won 2-1 in Gelsenkirchen last December.

Schalke returned the favour in April when Dortmund had captain Marco Reus and defender Marcus Wolf sent off in a 4-2 defeat, which effectively ended their team's title hopes, as Schalke picked up a key win to stave off relegation under Wagner's predecessor Huub Stevens.

This season, Schalke are a work in progress, following up a shock 3-1 win at title-contender Leipzig with a draw against Cologne, then defeat last weekend to mid-table Hoffenheim.

Their playmaker Amine Harit is one to watch as is England Under-21 right back Jonjoe Kenny, on-loan from Everton.

"I have experiences in this type of fixture from playing in the Merseyside derby for Everton against Liverpool," Kenny said.

"I know what the fans expect from us, and how hard we need to work.

"You can tell when there's a derby around the corner and that it's no ordinary match."

In the wake of a lacklustre 2-0 midweek defeat at Inter Milan in the Champions League, Dortmund coach Lucien Favre has the extra pressure of media speculation that Jose Mourinho is waiting to take charge if the Swiss is fired.

Favre has said he is "not okay" with the rumours and sporting director Michael Zorc insisted there are no such discussions among senior club figures as "we are happy that we have Lucien Favre."