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By Alasdair Lamont at the Pepsi Arena, Warsaw

By Alasdair Lamont at the Pepsi Arena, Warsaw Senior football reporter, BBC Scotland

Radovic's second put Legia in front and the forward later set up the hosts' third

Ronny Deila suffered a nightmare first loss as Celtic boss with a heavy defeat by Legia Warsaw in the Champions League third qualifying round first leg.

Celtic had taken an early lead in Poland with a curling shot into the top corner from Callum McGregor.

However, Miroslav Radovic scored twice, and it got worse before half-time when Efe Ambrose was sent off.

Ivica Vrdoljak twice missed from the penalty spot, but Michal Zyro and Jakub Kosecki both found the net late on.

If it was not for some heroic goalkeeping by Fraser Forster, this could have been a real embarrassment.

As it is, their hopes of progress are still alive, although they need to win at least 3-0, but the away goal and the balanced nature of the match in the first half will give Deila belief his side can turn the tie round.

However, the disjointed nature of Celtic's performance and their lack of ability to close the game down after being reduced to 10 men must be a concern.

There was no sign of the chaotic manner in which the game would unfold when McGregor added to his burgeoning reputation as he opened the scoring, just as he had in Iceland in the previous round.

The goal had a similar feel about it too as he cut in from the right before beating the goalkeeper at his near post, this time with a curling shot beyond the fingertips of the diving Dusan Kuciak.

But Celtic let the lead slip almost as soon as they had created it.

Efe Ambrose was sent off for Celtic in the first half

Radovic was allowed space inside the box and his well-hit effort was too powerful for Forster to keep out.

The game was extremely open, with neither defence looking entirely comfortable and more goals seemed a certainty.

And though Kris Commons and Teemu Pukki went close for Celtic it was the home side who took the lead.

Again Celtic's back-line - and Ambrose in particular - looked vulnerable and when Ondrej Duda headed across goal, Radovic was unmarked and gleefully slid in to beat Forster from close range.

McGregor forced a decent save from Kuciak but there was further bad news for Celtic to contend with before the interval.

As Michal Kucharczyk bore down on goal, Ambrose attempted to get a toe to the ball only to bring down the Legia man, leaving the referee a straightforward decision to brandish the red card.

Ambrose's departure meant Charlie Mulgrew dropped back to defence and it was the captain's careless challenge on Lukasz Broz that led to Legia being awarded a penalty.

But as the few Celtic fans in the stadium began to sense their Champions League dreams fading, they were granted a brief reprieve as Vrdoljak sent the spot-kick wide.

Legia pressed hard for the goals they hoped would put the tie beyond Celtic and Zyro rounded off an impressive performance with a headed goal following great work by the excellent Radovic.

Forster then saved a Vrdoljak penalty but in injury time substitute Kosecki added a fourth, to leave Celtic needing a monumental performance at Murrayfield next Wednesday if they are to avoid a place in the Europa League play-offs.

It could have been even worse for Celtic had Fraser Forster not saved a penalty