A 2-0 loss to Legia Warsaw at BT Murrayfield last night compounded the 4-1 defeat in Warsaw the previous week and means Celtic tumble out of the competition in the third qualifying round.
Deila accepted the prime responsibility for two abject performances but felt that the players had also had to take their share of the blame. The Norwegian, who succeeded Neil Lennon as manager in early June, believes a radical overhaul of his squad is required and is still confident that, despite the imminent loss of Champions League revenue in the season ahead, he will be given the funds needed to bring in the players he feels will improve the team.
"The players were fighting for everything they could but we didn't have the quality to break them down and win the game," he said. "So we still have to work on a lot of this. I also have to accept that that is the level [of performance] right now and we have to work from here.
"We have a big job to do to improve as a team so we can win the league and get into the Europa League too.
"Right now it's not good enough. That's what I can see. We need to make the squad better and bring in new players, that's what we're working on. But also we have to get the best out of what is here. "We will build up a new team. We have been in the Champions League for the last two years but this time we weren't good enough by far to get back in. It could be more difficult to attract players now but we will see how that goes. But we need players with pace, with ambition and who are young. I want to build a team that can last for many years.
"There were too many things
I saw that we must improve.
Right now the team is not good enough. I wasn't embarrassed
but I wasn't satisfied either.
It's of course my responsibility
but I also need time to get the players I want to come in."
Charlie Mulgrew admitted the prospect of no Champions League football is "devastating" but felt there was still plenty to aim
for, including a play-off tie
in the Europa League.
"It's devastating but the season's not over yet," said the midfielder. "We've just not done enough over the two games.
"There's no getting away from that - the fact we never did well
in both matches. But we need to quickly turn it around. There's still a big season to come. There's plenty to play for and we've still got a chance in Europe. We just need to be as positive as we can.
"I don't think we even came close to doing ourselves justice over the two legs. We knew what we had to do but we just didn't carry it through. They are a
well-organised side whereas
we are an evolving side.
We've a new manager who is still trying to get his ideas across.
'Without making any excuses, we're disappointed but we still have to be as positive as we can. We wanted a cavalry charge as well but it didn't quite materialise.
"But it's one competition and there's plenty to play for. We can still be in Europe so it's not the end of the world."