Djokovic's tactical adviser suggests under-arm serve vs Nadal

Former world number one Novak Djokovic's tactical adviser and ATP's strategy expert Craig O'Shannessy has suggested players to use the under-arm serve to counter Rafael Nadal in the clay court season. Explaining the reason behind such a tactic, O'Shannessy said "[Y]ou need to do things that make him uncomfortable, make him think twice, get inside his head."