Brighton boss Roberto de Zerbi concedes Moises Caicedo and Alexis Mac Allister are both set to leave this summer.
Caicedo is a target for Arsenal and Chelsea, while Mac Allister is interesting Manchester United and Liverpool.
After their 1-1 draw with Manchester City, De Zerbi said: "I don't know the future. I don't know the policy of these players.
"I think they deserve to play in another level.
"But we have to be ready to bring in more big player because we will play four competitions. The Europa League, the Premier League will be more tough and we have to be ready."
On qualifying for the Europa League, he also said: "It's a fantastic goal, we achieved an incredible target for Brighton club, Brighton players and Brighton coaches. We are very, very happy.
"Man City is the best team in the world I think. For us it was a very tough game. We deserve the point. we deserve the Europa League."