The 22-year-old, who has not featured for England since their opening win over Tunisia, is expected to feature for the Three Lions in Tuesday's clash with Colombia after recovering from a thigh strain.
Tottenham Hotspur midfielder Alli told reporters at a press conference that he is enjoying playing at the highest level of football.
"I believe I am ready. I feel like this is where I should be," the England man said. "Every situation and decision I've made is to get to this level. When you're growing up, you want to be playing at the World Cup and in the Champions League — the best competitions in the world.
"I've said many times before, there are moments you can't believe it's happening. At the same time, I've been playing a long time now. I was over the moon when selected and I've been working as hard as I can to help the team. So I'm not going to take it for granted. I'm still fighting every day to get int the team and prove myself as a player.
"I think the World Cup is the highest level — he best teams and players playing against each other. For me and as a team, we're not scared of anyone. We're not going to hide. We're confident in ourselves and will go out there and perform to the level we know we can."
England will face either Sweden or Switzerland in the quarter-finals, should Gareth Southgate's men get past Colombia.