In the drive for sustainability, companies are turning to Circular Economy (CE) principles, emphasizing resource conservation, waste reduction, and closed material loops. Strategies known as the R-principles (refuse, rethink, reduce, reuse, repair, refurbish, remanufacture, repurpose, recycle, and recover) guide CE implementation by maximizing resource use and minimizing waste disposal. Interestingly, the core focus of Lean Management (LM) on eliminating waste appears to align with goals of CE, providing a compelling opportunity for a synergistic approach to sustainability. This paper explores the combination of LM and CE through an in-depth examination of CE, an overview of LM, and a systematic literature review. The review builds upon 1,609 sources (2015-2024), reduced to 32 relevant papers, and adds expert insights to uncover conflicts, synergies, and success factors. The results are discussed with seven experts proficient in LM or CE to gain practical insights and explore implementation strategies. While LM targets immediate production gains, CE focuses on long-term resource preservation. This difference can create conflicts. LM methods like value stream mapping (VSM), total productive maintenance (TPM), or Green Lean Six Sigma can be adapted to achieve circular economy goals. Comprehensive key performance indicators (KPIs) and frameworks like sustainable VSM and environmental management systems (EMS) guide data-driven decision-making. Based on the literature review and expert interviews, further research should be conducted to measure the impact of LM and CE for (c)leaner and greener future.