South Africa's Chad le Clos has insisted that he faces a "tough battle" to defend his 200m butterfly title at the World Championships in Kazan tomorrow.

The 23-year-old eased into the final by winning his semi-final today, but he faces competition from Hungary's Laszlo Cseh.

The 12-time European champion clocked a time of 1:53.53 in the second semi-final to put him the fastest in the field in tomorrow's showdown.

"I think I'm going to need a personal best [to win]," Le Clos told Eurosport.

"I think it's going to be a really tight battle between us tomorrow night. I'm really excited - this is what I live for. It's going to be a dogfight on the way home."

Le Clos has won Olympic, World and Commonwealth gold in this event.