Kyle Lafferty is ruled out of crucial Slovenia tie

Gareth McAuley's first-half header put Northern Ireland on course for a memorable victory until the 65th minute in Belgrade, with goals from Marko Pantelic and Zoran Tosic eventually leaving them empty handed.

Now Worthington is left to assess the damage the match has done, both to their Group C prospects and, just as worryingly, the fitness of the squad to face Slovenia at Windsor Park on Tuesday.

Striker Kyle Lafferty was withdrawn at half-time against Serbia with a knee problem and his replacement, David Healy, is banned from the Slovenia match after picking up a booking.

That leaves only Warren Feeney and the unproven Liam Boyce as forward options, while Worthington confirmed there were other fitness concerns to be addressed over the weekend.

"We've got a few injuries we'll need to nurse over the next few days," said Worthington, who saw defenders Aaron Hughes and Jonny Evans require treatment during the game.

"Kyle has got a problem with his knee, it was tightening up all the way through the first half. He had to come off and David went on, and he got booked.

"I don't want to give too much away at the moment but we'll nurse the players over the next 48 hours and see who is available on Monday."

Asked if replacements would be considered once the squad returns to Belfast, Worthington added: "If someone can help me look then that would be most helpful, much appreciated. We've got what we've got. If there is someone available to come in we'll probably look at that but, certainly with Kyle, we'll give him every chance to see where he is at."

Worthington had targeted at least a point to keep his qualification plans on track at the Crvena Zvezda Stadium, which was bereft of home fans after crowd trouble caused Serbia's qualifier in Italy to be forfeited.

Despite taking nothing from the match, he hailed his side for putting in just the kind of gutsy display he had called for before the match.

"I thought it was a tremendous performance from the Northern Ireland players," he said. "In the first half the football they played was absolutely exceptional. They did the job very well and they got the all-important goal.

"But you know that at half-time Serbia are going to try and change something. They have very good players and you have to give credit to them.

"They went to a 4-2-4 and pushed players forward. Serbia are a very good team and they threw everyone forward in the second half.

"But I thought my players were fantastic.I thought the performance was excellent."

Serbia coach Vladimir Petrovic has called for Milan Jovanovic to be given more game time at Liverpool.

The former Standard Liege player endured a slow start to his Anfield career during former boss Roy Hodgson's rocky reign, and has featured just twice since Kenny Dalglish took over as caretaker manager.

He came to Merseyside with a reputation as one of Serbia's most talented players and started all three World Cup matches last summer, scoring the winner against Germany.

His lack of competitive action with the Reds has seen him slip out of Petrovic's first XI this season, but he put in a hugely impressive display in the win over Northern Ireland after being sent on for the second half. Petrovic said: "I am not surprised by Milan. I know he is a player who can play at a very high standard.

"It is impossible that such a good player would forget how to play football.

"He is special and he had a special desire to play for us here.

"In the past he has been one of our best players and I think he deserves more chances (with Liverpool]. If he gets chances he will soon be on the same level again."

Asked if Jovanovic should consider leaving Anfield in the summer, Petrovic was less forthcoming, adding: "Only he will answer whether he should leave or not. I don't want to speak about that."