NEIL Lennon last night admitted Celtic’s failure to qualify for the Champions League for the second season running could adversely affect his ability to strengthen his squad further in the transfer market.

Lennon conceded the Scottish champions only had themselves to blame for their painful exit from Europe’s premier club competition after their 4-3 defeat at Parkhead to Romanian rivals CFR Cluj and 5-4 aggregate loss.

The triple treble winners, who were knocked out in the third qualifying round by AEK Athens last year, now go into the Europa League play-off against either Sheriff Tiraspol of Moldova and AIK Stockholm of Sweden.

Lennon is hoping to add more players to his squad before the summer window closes at the end of August and has been linked with right back Robert Gumny of Lech Poznan and left back Birger Meling of Rosenborg.

However, the Northern Irishman, who is hoping to be handed a portion of the Scottish record £25 million fee Celtic received from Arsenal for Kieran Tierney last week, confessed the failure to reach the Champions League could mean they struggle to land their targets.

Asked if the Cluj loss would affect his transfer budget, he said: “I’m sure it will, but that’s not at the forefront of my mind at the minute. We all wanted Champions League football and we have only ourselves to blame for not getting that.

"The goals we conceded are crazy. You’ve got to do the basics well – you’ve got to stop crosses, close people down, get your head on things – and it was almost as if we scored and wanted to switch off and control the game.

"In the first half, we were way too passive, way too slow with the tempo, so we gave them a bit of a razz at half-time and we got the right response going 2-1 up. But we needed that two-goal cushion. It’s suicidal the goals we gave away tonight.

“The players are bitterly disappointed as they have missed out on a good opportunity. We all have. It’s a collective responsibility. We had enough quality out there to win the tie over the two legs.

"We conceded a poor goal away from home and could have scored a couple more away from home as well. Tonight we had good chances in the second half, but we didn’t take them. That would have put the tie beyond Cluj.”

Lennon left Boli Bolingoli, who Celtic signed for £3.5 million from Rapid Vienna last month, out of his starting line-up and fielded midfielder Callum McGregor at left back instead.

But he denied that had led to a defeat that will cost the Glasgow club, who led twice during the course of an extraordinary 90 minutes, in excess of £30 million.

"We wanted to get (Olivier) Ntcham into midfield because he's been playing well,” he said. "We wanted to have a couple of technicians in the field as well. Boli has been a bit up and down, but I don't think the decision to play Callum there affected the result.

"He set up the first goal for Jamesy (Forrest) and played very well. People can point at that (leaving Bolingoli out) but he did set up our equaliser and I thought he had a very good game. I don’t think the left side was really the problem tonight. Ntcham had a fine game as well.”

Lennon added: “It’s hugely disappointing for us all as a collective. We have to accept the criticism which comes our way - whether it be from the media, our own supporters or elsewhere. We need to regroup, qualify for the Europa League and make a strong claim in that.

"We’ve got to work with the players. We’ve got to raise their morale, first of all. We’re going to get a bit of criticism and that’s totally par for the course.

"We’ve worked really hard to get where we are we’ve basically thrown it away. We’ve got some good defenders, but for some reason they wanted to slow the game down.

"We need to be more ruthless at times. But then to score three times at home and still not win the game means we only have ourselves to blame. It's hugely disappointing for us all."