Wimbledon: Serena Williams, Novak Djokovic sail through to second round

Serena Williams moved past the halfway mark in her quest for a rare calendar year grand slam and Novak Djokovic clicked smoothly back into gear as the 129th Wimbledon Championships opened for business on Monday.

Serial title winner Williams, 33, has the Australian Open and French Open under her belt this year and her bid for a sixth Wimbledon crown began with a 6-4 6-1 victory over Russian debutant Margarita Gasparyan.

She swaggered on to Court One under sunny skies but took a while to warm to the task of chalking up a 22nd consecutive victory in grand slams, dropping her mighty serve in the opening game and looking rattled.

World number one Williams was warned for an audible obscenity when trailing 3-2 but soon transferred her aggression into some belting winners to overwhelm the world number 113.

Only two women in the professional era have won all four grand slams in the same year -- Margaret Court in 1970 and Steffi Graf in 1988 -- but 20-times major singles champion Williams is closing in.

Djokovic elected not to play any warm-up tournaments on grass prior to arriving in south west London but the 28-year-old defending champion quickly found his feet on the slick Centre Court turf against Germany's Philipp Kohlschreiber.

Like Swiss Stanislas Wawrinka, who crushed Djokovic's hopes of completing his career grand slam in the French Open final, Kohlschreiber boasts a lethal backhand but the world number 33 never threatened a first-day shock to rival Lleyton Hewitt's exit in 2003 when he was also trying to defend the title.

Djokovic chose his moments to push his shoulder against the door, breaking in the 10th game of the opening two sets, and sauntered through with minimum of fuss 6-4 6-4 6-4.

The crowd appreciated the Serb's display, which included trying to usher a small bird off the court in the first set.

"This is the cradle of our sport, it doesn't get any bigger than Wimbledon Centre Court and it's an honour and to be defending champion," Djokovic said after signing autographs on the world's most famous court.

Men's fourth seed Wawrinka was in action later on Centre Court againsy Portugal's Joao Sousa, after 2004 champion Maria Sharapova tackles British wildcard Johanna Konta.

Sixteen grand slam champions started out in the men's and women's singles, with several of them joining Djokovic and Williams in the second round.

Croatia's Marin Cilic, who joined the elite by winning the US Open last year, beat Hiroki Moriya of Japan 6-3 6-2 7-6(4) while Serbia's Ana Ivanovic, the 2008 French Open champion, powered past China's Xu Yifan 6-1 6-1.

Belarussian Victoria Azarenka, the former world number one, beat Anett Kontaveit of Estonia 6-2 6-1.

Spain's Carla Suarez Navarro became the biggest name to fall, the ninth seed thrashed 6-2 6-0 by Jelena Ostapenko.