Even without top scorer Patrik Schick, Bayer Leverkusen is well on the way to the Champions League.
Schick representative Lucas Alario paved the way for the fifth win in the seventh game of the year for the third-placed Bundesliga player, who also kept a clean sheet for the first time since mid-November.
Bayer had failed to qualify for the premier class four times in the past five years.
Schick, with 20 goals the second best league goalscorer after Bayern star Robert Lewandowski, will be absent for a few weeks due to a torn muscle fiber in his calf, according to the club.
For the Argentinian Alario, who wants to leave Bayer at the end of the season, it was only the third goal of the season.
Moussa Diaby, who added a brace (56/81), scored seven times in the last five games alone.
The table-14.
After just one defeat in eight games, Bielefeld once again suffered a setback.
A nice picture before kick-off: During the minute's silence, both teams mixed in the kick-off circle and actually commemorated the victims in Ukraine together.
For reasons of piety, Bayer refrained from playing carnival music in advance on the Saturday of the carnival.
Leverkusen's coach Gerardo Seoane had replaced almost half the starting eleven after the 2: 3 in Mainz last week and brought in five new ones.
Only the change from Alario to Schick was inevitable.
The guests from East Westphalia, who celebrated their first victory under coach Frank Kramer with a 2-0 win last March, started surprisingly bravely and aggressively - and were almost immediately punished.
A full 100 seconds were played when Paulinho ran alone from the halfway line towards the Arminia goal, but was cleverly pushed aside by Stefan Ortega and frittered away.
You could tell that the actually very agile Brazilian, who had only been in the starting XI once since the beginning of November, had a lack of match practice.
In the 24th minute, Paulinho almost forgot about this with a spectacular back-heel goal, but that too was prevented by the safe Ortega.
Another six minutes later, Paulinho was the provider of the opener, albeit happy.
He shot himself against the hand on a direct acceptance, Alario slotted the ball in and the goal passed the video review.
After the well-deserved lead at the break, Leverkusen remained dominant in the second half, but needed a long time to catch up.
Alario was offside when he thought he scored the second goal (48'), a shot by Jonathan Tah in his 200th Bundesliga game was blocked by Joakim Nilsson (55').
And then the 2-0 came through Diaby, who energetically asserted himself after a one-two with Florian Wirtz, who was again enthusiastic to play.
And the in-form French even followed suit.