LONDON: Novak Djokovic and Serena Williams target quickfire second round wins at Wimbledon on Wednesday to escape the brutal heat expected to send temperatures soaring to a tournament record of 35 degrees.

Defending champion Djokovic takes on Finnish veteran Jarkko Niemenin in the Centre Court opener.

World number 92 Nieminen is playing in his 12th and last Wimbledon having ended the All England Club career of 2002 champion Lleyton Hewitt over five sets in the first round.

Djokovic, also the 2011 champion, has a 5-1 career record over the 33-year-old Nieminen, a quarter-finalist in 2006.

The last time Djokovic lost in the second round at a Grand Slam was at 2008 Wimbledon, when as number three seed he was defeated by Marat Safin.

Fourth seed and French Open champion Stan Wawrinka takes on world number 48 Victor Estrella Burgos, only the second Dominican Republic player to take part in a Grand Slam.

Wawrinka recorded his best Wimbledon performance by reaching the quarter-finals in 2014.

Japanese fifth seed Kei Nishikori takes a 6-1 career lead into his second round match against Santiago Giraldo while 2014 semi-finalist Milos Raonic, the seventh seeded Canadian faces German veteran Tommy Haas.

At 37 years and 100 days old, Haas is bidding to become the oldest man to reach the third round at a Grand Slam since Jimmy Connors, who was just past his 39th birthday when he made the last 32 at the 1991 US Open.

US Open champion Marin Cilic, the ninth seed, meets Lithuania's Ricardas Berankis in a tussle between two former world junior number ones.

Five-time women's champion and top seed Williams faces Hungary's Timea Babos as she continues her bid to sweep a calendar Grand Slam.

Maria Sharapova, the 2004 champion and fourth seed, tackles Dutch qualifier Richel Hogenkamp.

Meanwhile organisers say a heat rule, which allows for a 10-minute break between the second and third sets of women's matches, could be used Wednesday when temperatures are expected to surge to around 35C on Wednesday.

However, the rule does not apply to the men's tour. The highest-ever temperature recorded at Wimbledon was 34C in 1976.

Despite the heat, All England Club chiefs say the Centre Court roof will not be closed to preserve the tournament's integrity as an outdoor event.