ROBERTO MANCINI admits his Inter players thought it was all over after they went 2-0 up inside the first 14 minutes at Celtic Park past night.

And after watching his Bhoys battle back to grab a 3-3 draw, Ronny Deila is convinced this tie still has a long, long way to go.

The Hoops boss is confident they can score in the San Siro on Thursday.

But Deila concedes they will have to be much better defensively if they are to send shock waves around Europe by progressing to the last-16 of the Europa League.

The element of surprise has now been lost as Inter know Celtic have guts to go with their guile.

And, having shown their superior fitness, Deila is hopeful they can take this tie right down to the wire.

He said: "We have to be a bit lucky and put together the best performance we have done so far.

"So it is going to be tough - but it is possible."

Celtic have to score in Milan, but Deila believes they have this in their armoury.

The manager said: "I believe we can score in the San Siro.

"The most important thing is that we can't concede as many as we did last night.

"We have a good chance to score, but defensively we have to be much better.

"Physically, we were very strong and ended the game better than them."

John Guidetti came off the bench to score the third goal, his first since November 30.

Mancini had a premonition that the striker he had under his charge at Manchester City would come back to haunt him.

Deila is happy his counterpart was proven correct and said of the Swede: "John has trained well, and when you train well you get your results.

"He had a good performance when he came on and got his goal as well."

Deila added: "It was an unbelievable football match with an unbelievable atmosphere.

"I'm so proud of the boys. To go two down early in the match, it is so hard to get back into it, especially against an Italian side.

"But we've talked the whole year about being brave, wanting the ball, trying to attack and creating.

"That's why I am very proud today because we caused them problems and got a result in the end.

"Of course, we wanted to get a better result, and we could have if we had not given them easy goals."

Craig Gordon, so often the hero on big European nights, was culpable for Inter's third.

But he showed strength of character to stay focused, and even pulled off an excellent save from a Xherdan Shaqiri free-kick in the final seconds to ensure Celtic held on to draw.

Deila is backing the 32-year-old to shrug off the disappointment of the performance, adding: "We would not be here if it was not for him.

"He is important for the team.

"He was unlucky, but the fans called his name after the last goal, and that is team spirit, and I really appreciate that.

"That helps everybody, and we got back into the game."