Each day of the Games we will bring ten facts you may or may not know about the great sporting spectacle that is the Olympics. Today we have some big names in athletics
The men's tennis final is a repeat of this year's Wimbledon climax - can Andy Murray beat Roger Federer this time? Murray is already assured of Britain's first medal in the men's singles since 1912, when Charles Dixon won a silver in the indoor event in Stockholm.
It's also the mixed doubles final at Wimbledon, where the reigning champions are the donor of a famous tennis trophy, Hazel Wightman, and a Titanic survivor, Dick Norris Williams. They won the title in Paris in 1924, and there hasn't been a mixed doubles event at the Olympics since.
On the track the undoubted highlight is the men's 100m final, scene of much drama over the years. Thomas Burke was the first champion, in Athens in 1896 in a time of 12.0 seconds: that wouldn't get you into the women's final now. Carl Lewis is the only man to retain the title, in 1988, but it needed the disqualification of Ben Johnson for him to do it. So history - and his flying team-mate Yohan Blake - is against Usain Bolt ...
Christine Ohuruogu - born in Newham, not far from the Olympic Stadium - tries to defend her 400m title today. She's the only Briton ever to win the gold, although there were silver medals for Ann Packer in 1964 and Lilian Board in 1968, and bronzes for Kathy Cook (1984) and Katharine Merry (2000). Packer was the hot favourite in Tokyo, but lost out to the Australian Betty Cuthbert, the only athlete ever to win individual gold medals at 100, 200 and 400m (she had done the sprint double at Melbourne eight years previously). But Packer made spectacular amends by winning the 800m, an event she didn't like very much.
The men's hammer is decided today: the first six Olympic titles (1900-1924) were all won by athletes representing the United States, although only the sixth one (Fred Tootell) was actually born there. The first five golds went to Irish-born naturalised Americans - John Flanagan, who won the first three, Matt McGrath and Pat Ryan.
The current world record in the men's hammer was set as long ago as 1986, by the Russian Yuriy Sedykh, the Olympic champion of 1976 and 1980 (and the 1988 silver medallist). Sedykh has been married twice, to two other Olympic gold medallists: first to Ludmila Kondratyeva, the 100m champion in Moscow in 1980, and now to Natalya Lisovskaya, the shot put gold medal-winner in 1988. Their daughter Alexia Sedykh won gold in the women's hammer at the 2010 Youth Olympics in Singapore.
We all know who isn't in the women's marathon, which takes place today. Paula Radcliffe's regrettable absence means that, failing a superhuman effort from one of the other local entrants, Britain's best results in this event are likely to remain the sixth places of Priscilla Welch in Los Angeles in 1984 (the first time the women's race was included in the Olympic programme) and the unsung Mara Yamauchi in Beijing in 2008.
In the sea off Weymouth and Portland it's crunch time in the men's Finn and Star classes, with British hopes high in both. Ben Ainslie is gunning for his third straight gold in the Finn. He also won in a Laser in 2000, and four sailing golds in a row would equal the record of Denmark's Paul Elvstrom, who won the Finn four times running between 1948 and 1960. In the Star, Iain Percy and Andrew Simpson are well placed to retain the title they won in Beijing. Percy also won gold in the Finn in Sydney.
The wrestling gets under way today at the ExCeL, with two medals at stake in the Greco-Roman category, in which use of the legs is not allowed. The freestyle wrestling, where almost anything goes, starts later in the week.
In the velodrome it's the climax of the men's omnium, a complicated six-stage event not unlike the decathlon. It's never been part of the Olympics before, but this time has replaced the individual pursuit (the event won by Bradley Wiggins in both 2004 and 2008), the points race, and the team Madison event. British hopes are pinned on Ed Clancy, already a double gold medallist in the team pursuit - but Clancy was only fourth at the world championships in Melbourne earlier this year, won by the home rider Glenn O'Shea.