The 84th-minute strike was the Swiss international's first Bundesliga goal in 15 months. It is perhaps unsurprising, then, that the 25-year-old was in a positive frame of mind after the match at the BayArena...
Question: Herr Derdiyok, congratulations on the win and your goal. Tell us how you feel...
Eren Derdiyok: I'm immensely relieved. The last six months have certainly been hard. I scored my last goal in 2012. It was important for me that, after getting knocked down, I got back up again. The team and the club have helped me back onto my feet. It may have taken a bit of time, but during the preparation for the second half of the season, I was able to send out a signal that I'm back.
Question: After three defeats, it was an incredibly important win for Bayer 04. Do you now feel you've made your own contribution to the club's league position? Do you feel you have really become part of this Leverkusen side?
Derdiyok: Absolutely. I'd done my duty before too, only it didn't always work out so well. Now we're into a new year and although we weren't able to win in Freiburg to start with, now we are back again and I hope we can keep it up.
Question: Is this goal also a step towards the World Cup in Brazil?
Derdiyok: I hope so, but I'm not giving too much thought to that. There's still a lot of time before then, but I'm heading in the right direction. If things carry on this way, then I'm sure I'll be involved.
Question: How big an issue had it been for you, going so long without scoring?
Derdiyok: It wasn't just that I wasn't scoring goals - I wasn't playing. When you only get a few games, then you can't score goals. Of course I was lacking self-confidence and you've got to show mental strength. Like I said, when you fall down, then you've got to lift yourself up again. Unfortunately that's happened a bit late for me, but that's why I am so enormously relieved. I've gained maturity and experience.
Question: After some good performances during the winter training camp, you were made out to be the real winner of the preparation period. Is this goal just a logical continuation of those good performances in training?
Derdiyok: I performed well in the training camp and in warm-up games and that is what I intended to do. I scored my goals again and felt relieved. Like I said, I showed that I'm back and I now want to carry this momentum forwards. My aim is to do my bit for the team's success and help the team further. The more I play, the better it is for me.
Question: How has the coach acted towards you in recent days and weeks? What kind of feedback has he given you?
Derdiyok: I think that the coach was happy with my performances in training. The body language has been good. From next week, we've got a difficult spell of games with many midweek matches and we're all going to be needed. If things carry on like this, I'm sure I'll get my share of games.
Question: What about your chances of starting?
Derdiyok: It certainly could happen when we're playing midweek matches that 'Kies' could get a bit tired, or that the coach wants to rotate things. That's not my decision, but in any case, I will be ready to show what I've got, even in the starting XI.
Interview by Tobias Gonscherowski