It’s tough to tell with the naked eye, but when a tennis ball is served the ball distorts into an almost unrecognizable shape. This is because tennis balls are squishy and bouncy and tennis rackets are strong and rigid. In other words, something’s got to give. In this case, it’s the ball.
The more you slow it down, the more flattened and deformed and goo-like the ball gets. At a certain point, it looks like the ball has just been absorbed and eaten alive by the tennis racket. Take a look at a tennis serve in slow-motion: