Cuéllar continued to be a star player for Flamengo in central midfield, helping to capture the 2019 Campeonato Carioca. He continued to be a transfer target for some European clubs. In August 2019, Cuéllar was be suspended from club activities indefinitely for refusing to travel with the team for the following league match, citing family matters. He was reintegrated into the squad ahead of Flamengo's Copa Libertadores quarter-final match against Internacional, which would be his final match for the club. On August 30, 2019, Saudi Arabian club Al-Hilal announced the signing of Cuéllar from Flamengo. The fee was reported to be €7.5m. Gustavo played for Colombia U17 in the 2009 FIFA U-17 World Cup, he appeared in all seven matches and scored two goals, both against Gambia in a 2-2 draw, as the team finished the tournament in fourth place. He also represented Colombia U20 in the 2011 South American U-20 Championship, he had five appearances and the team finished the tournament in the sixth place. On September 8, 2015 Gustavo debuted for Colombia as a starter in a 1-1 draw against Peru in Harrison, United States. In May 2018 he was named in Colombia’s preliminary 35 man squad for the 2018 FIFA World Cup in Russia. However, he did not make the final cut to 23. On May 30, 2019 Cuéllar was named by manager Carlos Queiroz to the 23-man squad for the 2019 Copa América in Brazil. He made one appearance in the group stage, appearing in the starting lineup and scoring the winning goal against Paraguay. Deportivo Cali  Junior  Flamengo  Al-Hilal