Bilic kept the team's aces firmly up his sleeve and the eight second-string players who started the match took full advantage with a flawless first-half performance.
"Everyone played well and it will be an extremely tough decision which four players to leave out in the final cut," Bilic told Croatian television.
"It will depend on injuries and our assessment where we need cover. Everyone is still in with a fair chance after a very good acid test for our Euro 2012 opener against Ireland in Poznan on June 10," said the 43-year old coach.
With the likes of Luka Modric watching from the VIP box, Croatia poured forward from the kick-off and the midfielder's Tottenham Hotspur team-mate Vedran Corluka fired Croatia into a 16th-minute lead.
Half-time substitutions saw several of Croatia's stalwarts enter the fray and two of them produced a superb third in the 81st minute when Ognjen Vukojevic capped a flowing move initiated by Niko Kranjcar.
"The game against Ireland will be crucial and I am very pleased with our first-half performance against Estonia because these two teams play kindred football," he said.
"Of course, the Irish are a much better team than the Estonians, whom they beat in the play-offs to reach the finals, but the next friendly against Norway will raise the bar and we will move up a gear."
