Ronny Deila conceded that his Celtic squad needs much improving following their Champions League catastrophe on Wednesday night but admits that could be difficult now that the group stage hopes ended at the hands of Legia Warsaw.

Trailing 4-1 from the first-leg of the third round qualifier in Poland last week, a difficult task for the Hoops at the BT Murrayfield stadium in Edinburgh became impossible when Michal Zyro notched in the 36th minute.

And when Michal Kucharczyk added a second on the hour mark it was all over, leaving the Parkhead side to nurse a 6-1 aggregate defeat while looking forward to dropping into the Europa League play-off.

Since taking over from Neil Lennon in June, Deila has so far only brought in goalkeeper Craig Gordon, the former Hearts and Sunderland keeper who was out of contract, and forward Jo Inge Berget on a six-month loan spell from Cardiff City - neither featured against Legia.

Asked how difficult it might be to attract more players to the club now that the incentive of the Champions League is not there, Deila said: "It could be more difficult of course, we will see how that goes.

"But we need players with pace, ambition and who are young. I want to build a team who could last for many years.

"It is my responsibility but I need time to get players in.

"I saw things which were good but there were too many things that need to improve.

"I have to accept that is the level right now and have to work from here.

"I have been here for six weeks but right now it is not good enough, from what I can see.

"We need to make the squad better by getting in new players but we also have to do the best with what is here.

"Right now, of course it is not good enough."

Legia Warsaw boss Henning Berg believes Deila, a fellow Norwegian, will come good at the Parkhead club.

The former Rangers defender said: "He has the experience, the knowledge and character.

"I hope Celtic give him time. That would be a wise thing to do.

"To get his ideas into the team in one month is very difficult.

"To play the important games so early in the season is difficult, we know that at Legia."