Koln moved 10 points clear of the relegation places with a hard-fought 2-1 win over high-flying Bayer Leverkusen at BayArena, damaging the hosts’ dreams of a top-six finish by inflicting their first defeat in 15 competitive matches.
Leverkusen and Koln arrived into the clash following frustrating results against maiden top-four challengers Union Berlin and Freiburg respectively, yet not many would have expected home goalkeeper Lukas Hradecky to swiftly concede just his second goal in over six hours of play.
Selke drew first blood with a swift header into the bottom corner, before Leverkusen retaliated with an assault of their own.
Taking advantage of a failed attack, Nadiem Amiri set a counter-attack in motion, ending with Amine Adli firing a first-time shot to punish an unsuspecting Koln backline.
However, that didn’t prevent Die Geissbocke from sticking to their plan of overpowering the opposition with their five-man diamond-shaped midfield.
And surely enough, Steffen Baumgart’s tactics paid dividends 10 minutes from the interval, as Jan Thielmann fed Selke from the right wing for the striker to register his brace with a poacher’s finish.
The second period began in bizarre fashion, as the away fans displayed their displeasure at bringing forward this clash to Friday, in light of Leverkusen’s UEFA Europa League semi-final showdown against AS Roma, by throwing tennis balls on the pitch.
That didn’t affect the tempo of the game though, as Xabi Alonso’s men continued to be challenged head-to-toe by a side eager to claim a third successive top-flight away victory.
However, As hard as Die Werkself toiled, it proved fruitless in the end, with the visitors ultimately tasting three straight wins on the road for the first time since 1996.
A first defeat in five home games also brings an end to an impressive run of nine league matches unbeaten for Leverkusen, who now must negotiate a tricky trip to Roma next week.
Meanwhile, Steffen Baumgart will go home a happy man after winning just a second touchline meeting with Leverkusen in seven encounters - a win that also seals a first Bundesliga victory on a Friday for the visitors in seven attempts.
A third victory in four matches leapfrogged Thomas Reis’ men over three of their relegation rivals while denting Mainz’s European ambitions in the process.
It was a back and forth affair from the off, as the raucous crowd inside in MEWA Arena was treated to some high energy football.
The home fans were stunned just before the half-hour mark however, as the in-form Bulter slotted home Schalke’s opener from the edge of the box in style to snatch the lead for the visitors.
Die Nullfunfer clawed their way back into the match in the final 15 minutes of the half, but struggled to break down a unified Schalke rearguard that were hell-bent on protecting their lead.
Mainz finally found their equaliser after the restart, as Leandro Barreiro darted into the back post to tap home a flicked header from a corner kick.
The home crowd’s celebrations did not last long however, as Schalke reclaimed their lead on the stroke of the hour mark thanks to Tom Krauss, who finished off a superb one-two with Kenan Karaman from close range.
The twists would not stop there, as Aaron Caricol fired home a fantastic free-kick from 25 yards to beat Alexander Schwolow and restore parity with just 20 minutes remaining in this topsy-turvy affair.
The drama would last until the very last minute, as Schalke were awarded a penalty-kick in the 101st minute of this ding-dong affair, as a VAR review revealed Bulter was taken down in the box deep into stoppage time.
The subsequent spot-kick was dispatched with aplomb by Schalke’s new hero, as Bulter snatched all three points for the Konigsblauen to pull them out of the bottom three with just three rounds of the Bundesliga season remaining.