Abstract: Generative artificial intelligence is fundamentally reshaping the collaborative foundations of knowledge work. This article synthesizes findings from a large-scale field experiment involving 776 professionals at Procter & Gamble to examine how GenAI transforms three core pillars of teamwork: performance outcomes, expertise integration, and social engagement. Results demonstrate that AI-enabled individuals achieve solution quality comparable to human teams, effectively replicating traditional collaborative benefits while breaking down functional silos between technical and commercial domains. Contrary to concerns about technology-driven isolation, participants reported significantly more positive emotions when working with AI. These patterns suggest organizations must move beyond viewing AI as merely another productivity tool and instead recognize its role as a "cybernetic teammate" capable of redistributing expertise, accelerating innovation cycles, and fundamentally altering optimal team structures. Evidence-based organizational responses include reimagining team composition, developing sophisticated AI-interaction capabilities, redesigning performance expectations around AI-augmented workflows, and building governance frameworks that balance efficiency gains with sustained human skill development.