Juan Martin Del Potro claimed a shock victory Venus Williams and sister Serena both battled through to the third round ©Getty Images

Fourth seed Stanislas Wawrinka of Switzerland crashed out of Wimbledon with a shock second round defeat to Argentina’s Juan Martin del Potro as organisers confirmed matches will take place on the middle Sunday to help ease the growing backlog for the first time since 2004.

Del Potro, the winner of the US Open in 2009, has suffered a torrid run of injuries and is making his first Grand Slam appearance since 2014 at the event at the All England Club.

Few gave him much hope of overcoming Wawrinka, the 2015 French Open champion, but Del Potro rolled back the years with a vintage display on his way to a 3-6, 6-3, 7-6, 6-3 victory.

The Argentine, who is currently ranked at 165th in the world, will next face France's 32nd seed Lucas Pouille or American Donald Young.

World number one and defending champion Novak Djokovic has a mountain to climb as he trails American Sam Querrey by two sets to love, with the rain perhaps coming at the perfect time for the Serbian.

Djokovic, the current holder of all four Grand Slams, is 6-7, 1-6 down to the big-serving Querrey, who may rue the timing of the rain delay.

The weather once again took centre stage as vast swathes of matches were suspended throughout the afternoon due to persistent rainfall.

There have been a total of 10 rain delays in the opening five days of the tournament and the weather has caused concern among organisers.

They have given the go-ahead to stage matches on the middle Sunday, traditionally the event’s rest day, for only the fourth time in the history of Wimbledon.

The most frustrating intervention of the weather came when Venus Williams had match point in her clash with Daria Kasatkina of Russia.

Venus Williams and sister Serena both battled through to the third round ©Getty Images
Venus Williams and sister Serena both battled through to the third round ©Getty Images

The American, a five-time Wimbledon champion, was unable to close out the win initially before she progressed courtesy of a 7-5, 4-6, 10-8 triumph over the battling teenager.

Sister Serena, the defending champion, also survived a scare as she needed three sets to get past world number 65 and compatriot Christina McHale 6-7, 6-2, 6-4.

Elsewhere, controversial Australian Nick Kyrgios, who has withdrawn from the Rio 2016 Olympic tennis tournament due to an ongoing spat with the Australian Olympic Committee, negotiated his tough contest with German Dustin Brown in five sets.

In a clash where both players demonstrated more than the occasional flash of brilliance, Kyrgios was unphased by the weather delays and eventually sealed a 6-7, 6-1, 2-6, 6-4, 6-4 win.

Seven-time world champion Roger Federer of Switzerland is also through as he beat Britain's Dan Evans 6-4 6-2 6-2.