Croatia's coach Slaven Bilic conceded he had failed to pick the right starting line-up and tactics for their 2-2 World Cup qualifying home draw with Ukraine on Saturday.
Bilic, bidding to take Croatia to their seventh major tournament in eight attempts since they became an independent nation in 1991, substituted the lacklustre midfield duo of Ivan Juric and Ivan Rakitic at half-time.
Their replacements Ognjen Vukojevic and Jerko Leko reinvigorated Croatia after the break, but the hosts avoided what could have been a costly defeat thanks only to a fortuitous, deflected equaliser from Luka Modric.
"We had worked on two different strategies for a month in the build-up to the match and unfortunately, we picked the wrong one," Bilic told Croatian media after the match.
"We tried with a standard formation in the first half, it didn't work so we made changes and played with two defensive midfielders in the second half.
"This qualifying campaign has not gone according to script and we are aware of the situation, but we still have a realistic chance of reaching the World Cup finals."
The result left Croatia's hopes of reaching next year's tournament in South Africa hanging in the balance, as they trail Group Six leaders England by seven points.
England have a maximum 18 points from six games. Second-placed Croatia have 11 from six, with Belarus, on nine points from five games, and Ukraine who have eight from five, closing in on the runners-up spot.
Only the nine European group winners qualify automatically while the eight best runners up will lock horns in a two-leg play-off for another four berths.
Bilic believes a pair of wins in Croatia's upcoming two fixtures against Belarus would leave his team on course before the clash with England at Wembley and a tricky trip to Kazakhstan in their final game.
"It's still in our hands and we have to focus on improving our own performances rather than wait for our rivals to slip up," he said.
"The first game is in August, it's a strange time of the year to play a World Cup qualifier but it could work for us because the players will be fresh and raring to go after the summer break."