Yomif Kejelcha has smashed the half-marathon world record, running a staggering 56 minutes and 51 seconds at the Media Maratón Ciudad de Buenos Aires in Argentina on Sunday.The Ethiopian shaved 29 seconds off the previous mark of 57:20, which had been set by Uganda's Jacob Kiplimo in Lisbon in March.Kejelcha's time and that of the record he just beat are still subject to ratification by World Athletics.The Media Maratón Ciudad de Buenos Aires is a World Athletics Label road race and took place under favourable conditions of 6 degrees Celsius and with a slight breeze.Tadese Worku (59:20) and Bereket Nega (1:00:20) of Ethiopia completed the podium."I'm over the moon," Kejelcha told World Athletics."I'm super happy and right now I don't feel any tiredness I'm very grateful."At the historic Estadio Monumental, Kejelcha showed off his new record on a new River Plate shirt, although would have been disappointed as Vélez Sarsfield came from 2-0 down to draw 2-2 in their Argentine Primera División clash