Team GB continued their remarkable swimming turnaround as Siobhan Marie O'Connor and the men's 4x200m freestyle relay team both won silver on another day of near-misses at the Rio 2016 Olympic Games. Though the team's medal haul has grown to six, Great Britain were left to rue several opportunities to improve that tally as their pre-Games medal target 48 looks increasinly ambitious.
O'Connor - who has suffered from ulcerative colitis since 2013 - won GB's first ever IM Olympic medal as she pushed Hungary's Katinka Hosszu all the way in a thrilling contest. Meanwhile, the men's relay quartet added to their world title with their best Olympic performance for 108 years finishing behind the team from the United States, whose anchor leg swimmer Michael Phelps took his gold medal tally at the Olympics to 21.
Andrew Willis could yet add to GB's medal tally in the swimming competition after qualifying second fastest for the final of the men's 200m breaststroke with a personal best time of two minutes and 7.73 seconds.
Phelps and Katie Ledecky ensured the gold rush continued for the USA. Phelps first claimed his 20th Olympic gold after winning the men's 200m butterfly - overcoming fourth place Chad le Clos in the process - after Ledecky won her second gold of the Games in the women's 200m freestyle.
Away from the Olympic Aquatics Stadium, David Florence was unable to convert his status as the reigning world champion and number one ranked canoeist as he finished a disappointing last in the men's C1. Florence had qualified fastest for the semi-final and though the 34-year-old squeezed into the top ten and reached the final, a run littered with mistakes saw him fail to trouble the podium places.
As the US team led by Simeone Biles cruised to gold in the women's gymnastic team final, Britain fell short in attempts to match their World Championship bronze as they finished fifth. Ellie Downie recovered from suffering a neck injury during qualifying to appear on all four pieces of apparatus but it wasn't enough as Russia and China completed the top three.
Diving duo Sonia Couch and Lois Toulson were unable to match the performance of Tom Daley and Daniel Goodfellow, who won bronze in the men's synchronised 10m platform, as they finished fifth in the women's event. The British pair were fourth going into the final dive but couldn't respond to the effort from Canada, who took the bronze behind China and Malaysia.
Though Britain continue to underwhelm in Rio, they still have medal contenders in both men's and women's tennis singles draws after British number ones Andy Murray and Johanna Konta were both victorious on day four. Murray completed a routine win over Juan Monaco, before Konta prevailed after a three-hour epic with Russia's Svetlana Kuznetsova.
Meanwhile, defending champion Serena Williams was knocked out by Elina Svitolina in straight sets as the women's draw was blown wide open. The American 22-time grand slam winner followed Garbine Muguruza in exiting the competition at the third round, after the Spainard was shocked by Monica Puig.
Aiming to go at least one better than their female counterparts, Great Britain's men won their opening two pool matches in the rugby sevens. Victories over Kenya and Japan - who earlier overcame a New Zealand team who will be without World Cup winner Sonny Bill Williams for the rest of the competition due to injury - set GB up perfectly for the second day of competition when they take on the All Blacks.
Katherine Grainger's hopes of retaining her Olympic title from London remain alive after she and partner Vicky Thornley qualified for the women's double sculls final. Alan Sinclair and Stewart Innes are also into the men's pair final while John Collins and Jonathan Walton progressed to the men's double sculls final.
But there was disappointment for the men's lightweight four and reigning lightweight double sculls Olympic champions Katherine Copeland and Sophie Hosking, as both boats failed to reach their respective finals.
Britain suffered a fourth exit from the men's boxing competition as Wales' Joe Cordina crashed out of the 60kg class at the hands of Uzbekistan's Hurshid Tojibaev. Cordina showed flashes of inspiration during the three-round encounter but lost by a split decision in cruel circumstances.