He has also worked frequently as a video assistant referee (VAR), including in the second leg of the 2018 Copa Libertadores Finals, the 2019 Copa Libertadores Final and the first leg of the 2020 Recopa Sudamericana.[8][9][10] He was appointed as a VAR for the 2019 FIFA Club World Cup in Qatar,[11][12] and was assigned to three matches including the final between Liverpool of England and Flamengo of Brazil.[13][14][15] Due to health reasons, Ostojich replaced his compatriot Leodán González as a referee at the 2020 FIFA Club World Cup, held in February 2021 in Qatar.[16][17] He was selected to officiate a second round match between Mexican club UANL and South Korean club Ulsan Hyundai, as well as the final between German club Bayern Munich and UANL.[11]