The Scottish champions looked set for a humbling defeat when they trailed 2-0 after just 13 minutes but got back on level terms before 30 minutes had been played. Inter took the lead on the stroke of half-time, thanks to a second error of the night from goalkeeper Craig Gordon.
But substitute John Guidetti’s stoppage time goal earned Celtic a merited draw on the night. While Inter are firm favourites to win this last 32 tie, Deila is adamant his team are capable of upsetting the odds in next Thursday’s second leg at the San Siro.
“It’s going to very very tough now,” said Deila. “We have to be lucky and put together the best performance so far under my command. But it’s possible so we are looking forward to the game.
“I believe we can score in the San Siro. The most important thing is not to concede as we did tonight. Defensively, we have to be much better.
“I did not have good thoughts at 2-0 down, I have to admit that. It was a very tough start. We actually started well and had them under pressure, but then it was just too easy for them to score. I was very worried but we showed a good mentality to get back into the game.
“It was an unbelievable football match with an unbelievable atmosphere. I’m so proud of the boys today. At 2-0 down, it’s so hard to get back, especially against Italian teams
“We talked earlier in the week about being brave, wanting the ball and trying to create things that’s why I’m very proud today. We caused them problems but it’s a pity we gave them two easy goals.”
Deila, however, insisted Gordon does not deserve to be singled out for criticism.
“I could say a lot of things about Craig,” said Deila. “We wouldn’t be here if not for him, we would he having a Thursday off. We wouldn’t have qualified if not for his saves in the group stage. He was unlucky tonight.
“But the fans, when they called his name after he conceded the third goal, were brilliant. That’s team spirit and I really appreciated that. That’s how we got back into the game, a lot of it is down to the fans.
“I was happy the fans were happy after the game. That’s because they saw we fought for 90 minutes and wanted to play attacking football. The players also saw it is possible to create chances at this level.
“Physically, we were very strong and finished the game better than Inter. So we got answers tonight about a lot of our players.
“John Guidetti has been in good focus lately. He has trained well and when you do that you get results. It was a good performance when he came on and a good goal as well. Stuart Armstrong and Gary Mackay-Steven also did well. They are going to give a lot to the team. They have only been here two weeks and when they get used to the systems and how we train they will be even better. I’m delighted with them.”
Inter manager Roberto Mancini was frustrated at the manner in which his team twice gave away a winning position on the night.
“I think we played a good game, starting the game very well,” said Mancini. “But maybe after we scored two goals we thought it was an easy game.
“We are young team but we allowed Celtic back into the game. In the end it’s still a good result for us but after the start we had it’s not good enough. We need to play better in the next leg. We know Celtic is a good team that plays good football. But being 2-0 up, then 3-2 up and then drawing, it’s disappointing. I feel we played too much in our own half in the second half.
“It will be a different match in Italy. We will have our supporters like Celtic did with their great fans. Being at home will be an advantage.”