A qualifier will represent Serena Williams' first opponent at Wimbledon as the world number one seeks to retain the only grand slam title she now holds.

Williams has lost two major finals in 2016, to Angelique Kerber and Garbine Muguruza, who were each placed in the bottom half of Friday's draw along with Simona Halep and Serena's elder sister Venus.

Agnieszka Radwanska, Belinda Bencic and two-time winner Petra Kvitova loom as the most dangerous opponents in Serena's half, but the reigning champion must wait to discover who she will face first up.

Fresh from her victory in the French Open, Muguruza - who lost last year's Wimbledon final to Serena - will take on Camila Giorgi in round one.

Radwanska starts her campaign against Kateryna Kozlova, Halep meets Anna Karolina Schmiedlova, Kvitova opens up against Sorana Cirstea and Kerber's round-one opponent is Great Britain's Laura Robson, who won in three sets when the pair faced off at the same stage in 2011.

Another Brit, Heather Watson, gave Serena a huge scare in last year's third round and a repeat of that clash could also be in the offing, providing Watson can beat Annika Beck and 31st seed Kristina Mladenovic.