Bayer 04 Leverkusen Fußball GmbH, also known as Bayer 04 Leverkusen (German: [ˌbaɪ̯ɐ ˈleːvɐˌkuːzn̩]), Bayer Leverkusen, or simply Leverkusen, is a German professional football club based in Leverkusen in the state of North Rhine-Westphalia.