LONDON, June 25 (Reuters) - Men"s defending Wimbledon champion Novak Djokovic will face British teenage wildcard Jack Draper in his opening match but Simona Halep, the women"s winner at the last championships in 2019, will not feature after withdrawing on Friday. World number one Djokovic is halfway to a calendar-year Grand Slam after winning the Australian and French Open titles, taking his overall tally to 19 majors. Draper, 19, will be making his Grand Slam main draw debut. Romanian Halep announced earlier on Friday that she would be pulling out of the tournament with a calf injury that prevented her from playing at the French Open. read more Serena Williams, who Halep beat to won the title in 2019, will begin her latest quest to claim a record-equalling 24 Grand Slam titles, against Aliaksandra Sasnovich of Belarus. Women"s top seed Ash Barty of Australia will face a first-round match against Spain"s Carla Suarez Navarro who recently returned to action having recovered from cancer. read more Britain"s twice champion Andy Murray, taking part in the singles for the first time since 2017 after two hip surgeries, was drawn to play Georgian 24th seed Nikoloz Basilashvili. Eight-time Wimbledon champion Roger Federer, who turns 40 this year, takes on Frenchman Adrian Mannarino in round one. PILOT EVENT Wimbledon is returning this year after the 2020championships were cancelled because of the COVID-19 pandemic. The tournament is a government-approved "pilot event" with a minimum 50% capacity, rising to a full 15,000 attendance for the men"s and women"s singles finals on Centre Court. read more Should Djokovic avoid a first-round shock he could play South Africa"s Kevin Anderson in the second round, which would be a repeat of the 2018 final. His prospective semi-final opponent is third seed Stefanos Tsitsipas who he beat in this month"s French Open final. Men"s second seed Daniil Medvedev opens against Germany"s Jan-Lennard Struff with a potential clash against Croatia"s former runner-up Marin Cilic lurking in round three. Serena Williams has been stuck on 23 Grand Slam titles since winning the 2017 Australian Open and her love of Wimbledon"s grass courts offers another opportunity to match the record of Australian Margaret Court. Her draw looks reasonably kind too. The sixth seed"s first big test could be Germany"s 25th seed Angelique Kerber. American teenager Coco Gauff, who took Wimbledon by storm when she reached the fourth round as a 15-year-old in 2019, could face Williams in the last 16. Gauff plays British wildcard Francesca Jones in the first round. The standout match of the women"s opening round sees twice Wimbledon champion Petra Kvitova, seeded 10, up against former U.S. Open champion Sloane Stephens.