Dimitrios Grammozis is Schalke's fifth head coach this season and takes charge with the Royal Blues having won just one league game all season.
Bayern Munich’s closest challengers, RB Leipzig and Bayer Leverkusen, both lost in the Bundesliga on Saturday to give the eight-time defending champions a chance to move seven points clear at the top.
The victory was Leverkusen's first in five league games and puts them second on goal difference, level on 32 points with RB Leipzig, who host Union Berlin on Wednesday.
For the second consecutive Saturday, Leipzig, who lost 3-1 last weekend at home to Borussia Dortmund, missed out on first place.
European football matchday: Chelsea visit stubborn Fulham in Premier League; PSG aim to secure top spot in Ligue 1
After a six-game run featuring four losses, Chelsea's expensively assembled team has dropped to ninth place — 10 points off the lead — ahead of a London derby at Fulham in the Premier League.
Bundesliga: Borussia Dortmund's Erling Haaland back in action as German top-flight league returns post winter break
Haaland has missed the last four league games and the last seven in all competitions after picking up a hamstring injury in early December.
Lewandowski, who played for Dortmund between 2010 and 2014, took his tally to 17 goals in 13 games against his former club. He also clocked up his 11th goal in just six Bundesliga appearances for Bayern so far this season.
Dortmund had three times as many shots on goal and dominated with 80 percent possession, which left their Swiss coach Lucian Favre to admit, "we are very disappointed, it's hard to accept this defeat".
Bundesliga: Robert Lewandowski breaks goalscoring record; Erling Haaland brace helps Dortmund secure second place
It means Dortmund are assured of second place with one game of the season remaining. Despite defeat, Leipzig are virtually assured of Champions League football next season.
Bundesliga: Mainz secure victory over Borussia Dortmund; Leipzig drop points after draw against Dusseldorf
Fortuna Düsseldorf stunned Leipzig with two late goals to draw 2-2 in the Bundesliga on Wednesday and boost their hopes of avoiding relegation.
Bundesliga: Bayern Munich inch closer to eighth straight title with thrashing of Fortuna Dusseldorf; Hertha Berlin beat Augsburg
Robert Lewandowski scored twice as Bayern Munich took a confident step closer to an eighth straight German title with a 5-0 demolition of Fortuna Dusseldorf in the Bundesliga.
Bundesliga: Krzysztof Piatek’s late penalty helps Hertha Berlin draw 2-2 against RB Leipzig; Dusseldorf beat Schalke 2-1
RB Leipzig missed the chance to move second in the Bundesliga after visiting Hertha Berlin scored a late equaliser in a 2-2 draw on Wednesday.
Bundesliga: Serge Gnabry scores twice as Bayern Munich thrash Cologne 4-1; Schalke play out goalless draw against Mainz
Serge Gnabry scored twice as Bayern Munich beat Cologne 4-1 on Sunday to reclaim the top spot in the Bundesliga.
Bundesliga: Bayern Munich take top spot after Leipzig drop points; Borussia Dortmund thrash Union Berlin 5-0
Bayern Munich scored three goals in the opening 26 minutes to defeat Mainz 3-1 away on Saturday and go a point clear at the top of the Bundesliga with their sixth straight win.
Bundesliga: Struggling Mainz sack head coach Sandro Schwarz after worst-ever start to domestic season
Defeat to Union saw Mainz drop into the bottom three after losing eight of their first 11 league games this season - the worst start to a season in the club's history
Amine Harit's superb last-minute goal saw Schalke snatch a dramatic win over Mainz and move to second in the Bundesliga on Friday, level on points with league leaders RB Leipzig.
Bundesliga: Union Berlin stun Borussia Dortmund to notch historic first-ever league win; Bayern Munich thrash Mainz
Union Berlin pulled off perhaps the biggest victory in their turbulent history, defeating Borussia Dortmund 3-1 at the Stadion An der Alten Foersterei.
Bundesliga: Bayern Munich pin hope on Robert Lewandowski against struggling Mainz; Dortmund to play without Thorgan Hazard
Two days after signing a new contract which will keep him at the club until 2023, the 31-year-old will be eager to add to the six goals he has also scored this season, even as champions Bayern dropped early points in the title race.
Premier League: Everton's new signing Jean-Philippe Gbamin ruled out for eight weeks due to thigh injury
Gbamin — who represented France at every age level including Under-21 before opting to play for his country of birth — signed a five-year contract with Everton on 2 August, filling the void left by Idrissa Gueye's move to French champions Paris Saint-Germain.
German Cup: Bundesliga sides Mainz and Augsburg suffer shock defeats; Schalke, Bayer Leverkusen progress
Augsburg's defence looked helpless in the first half as an own-goal from Marek Suchy and a well-worked goal from Ron Schallenberg gave SC Verl a shock 2-0 lead. Andre Hahn's 83rd minute penalty proved to be little more than a consolation effort.