LlamaIndex introduces a novel approach to document retrieval, combining embedding-based retrieval and LLM-powered reranking, to enhance document relevance in retrieval-augmented generation (RAG) systems. While embedding-based retrieval is fast and cost-effective, it can sometimes yield imprecise results, prompting the integration of LLMs to rerank documents in a second-stage process. This two-stage pipeline offers a compromise between speed and accuracy, demonstrated through experiments involving the Great Gatsby and the 2021 Lyft SEC 10-K. The method improves precision by using LLMs to refine the selection of documents retrieved in the first stage, although it incurs higher latency and cost. The study presents qualitative results, highlighting improvements over traditional embedding-based retrieval, and suggests further exploration of optimal configurations, alternative reranking methods, and scenarios where LLM-based retrieval might suffice independently.