Jamaica and South Africa set world U20 records in the women's and men's 4x100m, while Botswana and Nigeria ran world leads to win 4x400m gold as five days of action at the World U20 Championships ended on a high.The Jamaican quartet of Serena Cole, Tina Clayton, Kerrica Hill and Tia Clayton ran an inspired race to smash the previous world U20 record of 43.27 set by Germany four years ago to take their 12th women's 4x100m medal in World U20 Championships history and fifth 4x100m gold with a world record of 42.94.Winner of the women's 200m title, Christine Mboma, anchored the Namibian team to their first ever podium finish in the relays at the championships, a silver medal won with a time of 43.76, while Nigeria settled for bronze with a season's best of 43.90. That made them the country's first women's 4x100m medallists at the World U20 Championships since the first edition in 1986 where Tina Iheagwam, Caroline Nwajei, Falilat Ogunkoya and Mary Onyali also won bronze.
The South African squad comprising Mihlali Xhotyeni, 200m men's bronze medallist Sinesipho Dambile, Letlhogonolo Moleyane and 100m silver medallist Benjamin Richardson stormed to gold in 4x100m with a world U20 record of 38.51, finishing ahead of Jamaica who clocked 38.61, while Poland won bronze with a timing of 38.90.Botswana was the team to beat in the men's 4x400m, with Anthony Pesela, Busang Collen Kebinatshipi, Oreeditse Masede and Phenyo Bongani Majama racing to a world U20 lead of 3:05.22. Jamaica took the silver with a season's best of 3:05.76, while host team Kenya beat Nigeria to bronze with their time of 3:05.94.Having already won two gold medals in the women's 400m and mixed 4x400m respectively, Nigeria's emerging star in the quartermile Imaobong Nse Uko inspired her 4x400m teammates to a world U20 lead of 3:31.46 after putting the squad in pole position for gold, building on the good start from Opeyemi Oke and overtaking Jamaica's Aalliyah Francis to hand the baton to Ella Onojuvwevwo in first position.Favour Ofili, who had helped the 4x100m team to bronze less than an hour before, consolidated on the lead and anchored the team to gold, her third medal of the competition as Jamaica posted a season's best of 3:36.57 for silver. Italy's squad of Alessandra Iezzi, Federica Pansini, Angelica Ghergo and Alexandra Almici were the surprise bronze winners, returning a time of 3:37.18 to cross the line ahead of India.