Casteels was last week named as first choice for the tournament in Germany as Belgium do without Courtois, who had a row with coach Domenico Tedesco last year, then suffered a long-term injury but came back to help Real Madrid win the Champions League last month.
Casteels, who turns 32 this month, said his 13 years playing in the Bundesliga with Hoffenheim, Werder Bremen and VfL Wolfsburg would stand him in good stead for the tournament, where Belgium are in Group E and take on Romania, Slovakia and Ukraine.
"I don't feel any added pressure because I have to replace Courtois,” he told a press conference on Thursday.
“Everyone who is here wants to perform as well as possible. I will do that too. I don't feel any pressure, and I'm really no different on the practice field either than I was before when I was number two. I'm not going to do anything different now.
“It was good that the coach gave clarity before the tournament about the goalkeeping position. It was always good to know what the pecking order is,” he added.
Casteels has long been an understudy to Courtois in the national team and collected only 10 caps while waiting in the wings.
Belgium play their first game at Euro 2024 against Slovakia in Frankfurt on Monday.
