Inspired by the French Open tennis tournament which is on at the moment, a tweener is a between-the-legs shot, when a player runs to return a lob and doesn’t have time to turn round, so hits the ball backward between their legs. It’s generally a last reserve in competition, although it turns up a lot when people are showing off in exhibition matches.
Beloved of modern players like del Potro, Kyrgios and Radwańska, the tweener pioneer is retired Argentine player Guillermo Vilas. He used it a lot throughout his career in the 70s, and his version was called the ‘Gran Willy’ (literally ‘the great willy’, snigger – I don’t know why). In fact, he claims to have invented it (as does a French player by the name of Yannick Noah), but it’s a bit hard to prove this. Gabriela Sabatini was also a fan, and her version was called the ‘Sabatweenie’. Famously, Federer used a front-facing tweener to get himself a match point in the 2009 US Open semi-final, and called it ‘the greatest shot I ever hit in my life’. Here’s a video of some awesome tweeners.