First round: I'm weaker than Justin Bieber. He wins... Wait. I can overpower his singing with my amazing smartphone DEXP Ixion X4 - it has 3000 mAh battery, 4-core 1.2 GHz processor, 1GB of RAM, 5 Mp frontal camera, powerful videocore, high-quality details, supports 2 SIM-cards, up to 32GB SD card and Android 4.4! Sadly, it's made in China. Meh, I'm Russian and Kalmyk and that's not important. My smartphone will break it's own limits and will do Ultra Instinct - it will automatically do the loudest sound ever and will counterattack Justin Bieber's attacks via the song Ultimate Battle (Dragon Ball Super)! I win! Lol!
Second round: Justin Bieber's programming skills are poor. I have better programming skills! How I'm going to beat Bieber? Oh, yes! I'll throw tasty ultrahot meat at him! "It burns!" - says Justin Bieber. I win.