Skipper Aaron Hughes admitted it was not a good night for Northern Ireland as individual errors cost his side dear against Estonia in Tallinn.
Martin Vunk notched the opener for Estonia before Lee Camp let in a long distance Tarmo Kink effort to double the hosts' advantage.
Raio Piiroja headed into his own goal to hand Worthington's side a lifeline but substitute Sergei Zenjov restored Estonia's two-goal advantage when he scored after Gareth McAuley dwelt for too long on the ball..
Fellow substitute Kaimar Saag completed the rout with an injury time fourth to leave Northern Ireland fifth in Group C, five points behind second placed Serbia with two games remaining.
Afterwards Hughes rued the defensive errors, telling Sky Sports: "It's not often we make individual errors and we've made three or four in one game. Sometimes that happens and tonight just wasn't a good night for us.
"We actually, in spells of the game, played really well. We kept the ball well, we moved it, tried to create some chances and then we just sort of gave it away in bad areas and then it cost us."