Japan’s Naomi Osaka beat Czech Petra Kvitova in Australian Open final to win back-to-back Grand Slams and become the new world number one.

• Osaka, who replaces Simona Halep at the top of the rankings after the Romanian’s 48-week stint, becomes the first Asian player to be world number one.
• She is also the youngest to hold top spot since Denmark’s Caroline Wozniacki, then aged 20, took the ranking in 2010.

LEARNING WITH TIMES

The French Open is played on clay, which owes its red colour to the crushed brick which forms the upper layer of the surface. There are three layers in all – one of limestone, one of clinker and one of stone – as well as drainage pipes. Clay is the slowest of surfaces. Along with the Australian Open, Wimbledon and the US Open, the French Open is one of the four historic tennis tournaments which make up the legendary Grand Slam. The four tournaments all being played on different surfaces: Plexi cushion in Australia, Clay at Roland Garros, Grass at Wimbledon and Decoturf at the US Open. The Australian Open, French Open, Wimbledon and US Open are the four Grand Slam tournaments. The Grand Slam itinerary consists of the Australian Open in mid January, the French Open in May/June, Wimbledon in June/July, and the US Open in August/September.