A massive win for Leverkusen and their fans are understandably bouncing. All five of the Werkself's goals arrived in a barnstorming second half that leaves Union racing for the bus back to Berlin.
Speed check: The fastest player in the game after 90 minutes
B04 TAKING IT HOME
The pace has dropped, with Leverkusen looking content with their five goals for now. It's hard to fathom that this is the same team that produced the club's worst ever start to a season.
LEVERKUSEN ON FIRE
And they now have five. How Union would love this to end right here. Mitchel Bakker slides a left-footed finish across the goalkeeper and in at the far post. Incredible.
B04 WANT MORE
It's party time at the BayArena. Leverkusen are continuing to pour forward in search of more against an utterly shellshocked Union side who have had no answer whatsoever to this second half onslaught.
And now it is four! Hlozek diverts in with a back heel after some fantastic work from Amiri to get flash the ball across the face of goal.
It's been an incredible falling off from Union, who were done by a set piece at the start of this half and then two breakaway goals in quick succession. Urs Fischer looks understandably gloomy on the touchline.
DIABY GOES CLOSE
Diaby almost makes it 4-0, but a block prevents the Leverkusen man from adding to Union's pain.
Scenes! Leverkusen burst away from a Union corner yet again and they catch the visitors all over the shop. Bakker releases Diaby who slots in number three!
BAYER DOUBLE UP
Leverkusen are in heaven! It's an absolute howler from Grill, who tries to, and fails to control a backpass while outside his area, allowing Frimpong to nip in. Frimpong feeds Diaby who runs it through and scores!
Xabi Alonso opts to send Palacios into the mix for Demirbay. The latter doesn't look best pleased at having to come off.
GRILL CALLED INTO ACTION
Amiri whacks a low shot at goals from the edge of the box. Grill gets down to save and hold on.
GAME VERY MUCH ON
BAYER IN FRONT
Leverkusen lead! Demirbay's corner from the left is hooked in by Andrich at the back stick.
AWAY WE GO AGAIN
The ball is rolling in the second half ...
Not much for either set of fans to get excited about in what was a very low key first half in Leverkusen. Both sides will surely look to step up a couple of gears in the second half.
A jersey tug by Thorsby on Amiri prevents the latter from racing away. That's one more booking for Union.
Diogo Leite heads over the crossbar as the Berliners look to up the tempo slightly.
AMIRI OFF TARGET
A shot! Amiri has the ball on the edge of the Union box, has a look up and curls a right-footed effort over the crossbar. A rare sight of goal in this half.
Diaby works some space, gets into the Union area and slides an inviting ball across the box. No Leverkusen player can reach the pass.
GRILL IN ACTION
Grill races off his line to collect at the feet of Frimpong. The Union goalkeeper gets there, but slides outside of his box, gets to his feet and hoofs clear.
Speed check: The fastest player in the game after 30 minutes
JORDAN SEES YELLOW
Jordan downs Hincapie and is the latest Union player to be booked.
Khedira hauls down Frimpong, who was in full flight. Yellow card for the Union man.
LITTLE TO CHEER
Demirbay has a chance to throw one into the mixer from a free kick outside the area. A mix-up in communications follows, with the Leverkusen No. 10 passing the ball along the floor to nobody in particular. It's been that sort of game so far.
It's all Leverkusen, who are dominating the area in front of Union's box, although failing to make any inroads past that point. If they are to get through in the next few minutes, expect the lively Frimpong and Diaby to be involved.
ALL UP IN HIS GRILL
A couple of high balls into the Union area have allowed Lennart Grill - replacing the injured Frederik Ronnow today - to gain some early confidence, the custodian claiming with relative ease.
Both sides are looking to settle, Leverkusen probing, Union waiting patiently for an opening. Plenty of intrigue thus far.
We have kick off in Leverkusen ...
Both sides are out on the field and soaking up the terrific atmosphere inside the BayArena. Kick off is just moments away!
With an average age of 24.6, Leverkusen are collectively three years younger than their opponents today.
After recovering from a torn meniscus injury, Leverkusen attacker Karim Bellarabi is back in the Bayer squad for the first time since the beginning of August.
UNION TEAM NEWS
Urs Fischer also shows four changes to his side today after Union's Europa League efforts in the week. With goalkeeper Rönnow injured, Lennart Grill comes in to face his former club. Elsewhere, Baumgartl, Thorsby and Jordan are in for Doekhi, Haraguchi and Michel.
B04 TEAM NEWS
Xabi Alonso opts for four changes to the side that started the midweek scoreless draw against Brugge, with Schick, Hudson-Odoi, Palacios and Tah making way for Hlozek, Demirbay, Amiri and Hincapie.
Union coach Urs Fischer warned that his team "shouldn't look at the table," perhaps for fear of heights or, because the Irons' boss believes that opponents Leverkusen should not be where they are in the standings. "Many of [Bayer's] recent results are misleading when one looks at the performances," Fischer explained. "We have our plan and know what we have to do in order to take something home from this in the end," the tactician added.
"CREATE MORE CHANCES"
WATCH: UNION RIDING HIGH
SCHICK EXPECTED TO START FOR B04
As for the hosts, their own concerns up front have been eased by Patrik Schick featuring in the 0-0 draw with Club Bruges this week and the Czech striker should start at the BayArena today. Kerem Demirbay shook off a leg problem to return as a substitute against Bruges, but Karim Bellarabi and Charles Aranguiz remain doubts for the visit of Union. Florian Wirtz is back in training but short on match fitness.
DECISIONS IN ATTACK FOR FISCHER
Union coach Urs Fischer has a decision to make in attack, with usual front-two Sheraldo Becker and Jordan without a goal in five matches. Meanwhile, Sven Michel started and scored in Europe in midweek, while Kevin Behrens netted off the bench in the win over Borussia Mönchengladbach last weekend so could we see Fischer mix things up?
A very warm welcome to our live coverage of Leverkusen vs. Union, where the hosts start the day third from bottom and go up against a visiting outfit looking to move back into top spot. With ramifications at both ends of the table and so much quality on display, this should be a cracker. Kick-off is at 3.30pm CET, with team news dropping an hour prior to that.