Rafael Nadal into French Open final after Alexander Zverev injured in fall

Alexander Zverev retired from the French Open semi-finals after a fall (Christophe Ena/AP)

Rafael Nadal has reached the final of the French Open after opponent Alexander Zverev was forced to retire injured.

In distressing scenes, German third seed Zverev fell and injured himself at the end of the second set, yelling in pain as Nadal rushed around the net to help.