The Observer's 20 photographs of the week

South African President Jacob Zuma confirmed that Mandela's condition had become critical this week. Media companies have rented space along Vilikazi Street where Nelson Mandela lived from 1946. Here, on the street, a boy plays on scaffolding built for the television news crews Photograph: Chip Somodevilla/Getty

A woman cooks in Qunu where Nelson Mandela grew up. Barack Obama led a chorus of support for the 'hero for the world' en route to Johannesburg on his week-long tour of Africa Photograph: Carl De Souza/AFP

Before his arrival in South Africa, Barack and Michelle Obama were in Senegal. Here they look out from the Door of No Return while touring the House of Slaves at Goree Island off the coast of Dakar. This was the final exit point for Africans before being shipped off the continent as slaves Photograph: Saul Loeb/AFP

Senegalese performers wait for Barack Obama who is on his way to a meeting with Senegal's President Macky Sall at the Presidential Palace in Dakar Photograph: Jason Reed/Reuters

Palestinian children play outside their family's tent in a poverty-stricken quarter of the town of Younis, in the southern Gaza Strip Photograph: ALI ALI/EPA

At Wimbledon, on 'wounded Wednesday', seven players withdrew from the tournament with injury. Here Maria Sharapova of Russia slips during her match against Michelle Larcher De Brito. The third seed Sharapova was overheard calling the court 'dangerous' during her defeat Photograph: Stefan Wermuth/Reuters

Later on the same day, Ukraine's Sergiy Stakhovsky celebrates after beating Switzerland's Roger Federer to bring to an end Federer's run of 36 consecutive grand slam quarter-finals Photograph: Adrian Dennis/AFP

The demonstrations in Brazil against poor public services, corruption, the cost of living and extravagant spending on the World Cup continued this week in Brazil. Here, a man lies on the ground after he was injured by a projectile fired by police outside the Minerao stadium in Belo Horizonte Photograph: Felipe Dana/AP

And here, police officers confront demonstrators during the protest in Niteroi, Brazil Photograph: Yasuyoshi Chiba/AFP

Whistleblower Edward Snowden was scheduled to occupy this empty window seat aboard an Aeroflot flight from Moscow to Havana Photograph: Kirill Kudryavtsev/AFP

Chinese astronauts Zhang Xiaoguang, Nie Haisheng and Wang Yaping salute after exiting the re-entry capsule of the Shenzhou X spacecraft. The astronauts landed at the Inner Mongolia Autonomous Region of China after a 15-day trip to a prototype space station Photograph: ChinaFotoPress/Getty

A regular to this gallery, photographer Filippo Monteforte captures the moon over a traffic light in downtown Rome. The full moon at perigee, known as a supermoon, is the largest and closest full moon of the year. It appears 14% larger and 30% brighter than usual Photograph: Filippo Monteforte/AFP

Singer Justin Bieber performs in Los Angeles, California, during his Believe Tour Photograph: Mario Anzuoni/Reuters

Long-tailed mayflies, palingenia longicauda, mate on the surface of the Tisza river in Hungary. Millions of these mayflies engage in a frantic rush to mate and reproduce before they perish in just a few hours during the Tisza blooming season from late spring to early summer Photograph: Laszlo Balogh/Reuters

Stranded Indian pilgrims make their way down a mountain after a section of road was washed away in Govind Ghat. Up to 1,000 people in northern India are feared to have died in landslides and flash floods that have also left pilgrims and tourists stranded without food or water Photograph: Manan Vatsyayana/AFP

A member of the Afghan security force stands guard near the Presidential palace in Kabul. Taliban militants had targeted the presidential palace and the CIA office in central Kabul Photograph: Shah Marai/AFP

Palestinian girl Alaa Soboh participates in a skipping rope game during UN-run summer fun games week in Gaza City. Tens of thousands of children from the Gaza Strip spend part of their holidays in special summer camps. Some, organised by the UN, offer sports, art and dance classes. Others, laid on by Gaza's Islamist rulers Hamas, include fun and games, while seeking to reinforce religious values and awareness of the conflict with Israel Photograph: Mohammed Salem/Reuters

People enter the grotto of the Rhone glacier in the central Alps, Switzerland. The glacier is protected by blankets at this time of the year to keep ice melting to a minimum Photograph: Olivier Maire/EPA

Egyptian protesters wave their hands and hold national flags during an anti-President Mohammed Morsi demonstration in Tahrir Square, the focal point of the Egyptian uprising in Cairo Photograph: Amr Nabil/AP

The Lords of Lightning perform in Arcadia at the 2013 Glastonbury Festival at Worthy Farm Photograph: Ian Gavan/Getty Images