This is the battle that started it all: two hall-of-fame super-producers going beat for beat through their chart-topping discographies. The Verzuz series started as a one-off friendly face-off between Swizz Beatz and Timbaland, but they quickly switched from competitors to collaborators, continuing the series with new legends and turning it into one of the must-watch musical events of 2020. The collegial battles have featured some of hip-hop and R&B’s most beloved songwriters and producers squaring up and digging deep into their catalogs to remind us—and each other—how much work they’ve put in. Tim and Swizz immediately set a high standard for the series. Both producers were particularly dominant in the late '90s and early 2000s, but time isn’t the only thing that made the pairing make sense: The two were key figures in transforming the sound of rap and R&B in the new millennium, moving from nostalgic samples to futuristic synthesizers and incorporating the bouncy new beats emerging out of New Orleans and the South. Both had go-to crews that helped their respective sounds flourish—the Ruff Ryders’ raucous street rap for Swizz, Aaliyah's and Missy Elliott’s slinky, quirky melodies for Timbaland. And nonetheless, both producers landed some of their most memorable and successful cuts with the same artist, JAY-Z, often on the same albums. Dig deep into the undeniable catalogs of the Verzuz founders with this Cheat Sheet playlist, curated by Apple Music host Lowkey.