Naruto Shippuden Episode 28

Team Guy continues to fight their clones. Neji explains to each member of the team that they are growing weaker as the fight drags on, and their clones, being non-human, remain as strong as they were when they were formed. Lee realises that the only way for them to defeat their clones is to become stronger than they were when they first started fighting. After remembering their training, they remember their resolve to constantly become stronger. This gives them the strength needed to overpower and destroy their clones.