They have an 11-point lead on the second-place team, and a 13-point lead over their opponents on Friday, a fourth-place Bayer Leverkusen side that's hoping to shock the world.
Lewandowski, the Bundesliga's top-scorer with 15 goals in 17 games so far, is labouring with a knee injury while Hummels has a groin strain and the away match at Leverkusen's BayArena has come too early.
"Mark Uth is now the best German goal scorer in the Bundesliga and will really improve our attacking options from the summer", said Schalke sporting director Christian Heidel.
"They (Leverkusen) are a young, hungry and highly talented side which has a lot of imagination", said head coach Jupp Heynckes in yesterday's press conference.
- Heynckes to stay on?
Heynckes said: "Joshua Kimmich will travel with the team, but I have to think about if he will start".
Such is his authority and standing at the club - president Uli Hoeness described Heynckes' return as "getting six numbers in the lottery plus the jackpot" - he remains Bayern's No. 1 candidate for next season.
Bayern were five points adrift in the league when Heynckes, 72, replaced Carlo Ancelotti at the start of October, but built up a commanding lead as key rivals RB Leipzig and Borussia Dortmund faltered. "If we all stay fit that will definitely help, but we also need good combinations, lots of movement off the ball, plus to mix up the tempo".
Only Manuel Neuer and Thiago Alcantara, both long-term injury absentees, will be missing for their trip to Leverkusen though Heynckes will have new signing Sandro Wagner available, with the forward having joined from Hoffenheim. "He's a German worldwide with ambitions of going to the World Cup in Russian Federation".
Leverkusen boss Herrlich was on Tuesday fined 12,000 euros ($14,368) by the German FA for his theatrical sideline dive in a 1-0 German Cup win against Gladbach last month.