After a 1-0 defeat to Serbia on Friday, Worthington's side must win in Tallinn on Tuesday to be in with a chance of finishing second in Group C. But with Rangers centre forward Kyle Lafferty again missing with a calf injury, attacking options are limited.
Northern Ireland have scored just seven times in seven matches in this campaign, with five of those goals coming in two games against the Faroe Islands.
To make matters worse, four of those goals have come from Lafferty, fellow calf victim Paddy McCourt and the suspended Corry Evans. Those facts are not lost on Worthington, who has modest resources available to him.
Warren Feeney currently plies his trade in League Two with Plymouth, Josh McQuoid has yet to score at international level and record scorer David Healy, on the fringes at Rangers, has not registered since October 2008.
"Northern Ireland's biggest concern is the front, when Lafferty is out we haven't got another big striker and that's a situation which probably should have been addressed some five, six or even 10 years ago," said Worthington.
"We haven't got a Gerry Armstrong, we haven't got a Norman Whiteside, we haven't got a Billy Hamilton. If you look at those three strikers, in 1982 or 1986, you were able to score goals.
"But we are not prolific goalscorers and we are not going to score two or three goals against quality sides."
Healy has started the last two matches in Lafferty's absence and with 35 goals to his name, he is the top scorer in Northern Ireland's history.
He should, on paper at least, be an automatic stand-in for his club-mate at Le Coq Arena but Worthington harbours concerns over his match-fitness due to his peripheral role at Ibrox.
"I have to look at the options across the board because Estonia are a hard-working team. David played 70 minutes (against Serbia) but he isn't playing a lot of first-team football," said Worthington.
"I haven't named the team yet. Can David cope? We have to ask that because that is being fair to him and fair to us."
Although his side realistically need maximum points from their last three fixtures, Worthington has been impressed by the spirit among his players.
He expects Estonia to provide a stiff challenge, especially after a surprise victory in Slovenia last time out, but is hopeful of a positive result.
"There's no tension or pressure here. There's a very good spirit within the group," he said.
"We lost on Friday in an unfortunate way but that's football, the players have got over that and are looking forward to the game.
"The Estonian team will be tough to play against, they are a very hard-working side and it's unsurprising they've beaten Slovenia.
"But of course the aim is still to qualify. If you look at the group there are three or four teams looking for the second place so there's all to play for and we'll be doing that tomorrow night."
Jonny Evans, like brother Corry, is suspended having picked up a second booking against Serbia, but Sammy Clingan is expected to return after withdrawing from that match with illness.