PAUL MERSON has told Celtic to put aside any hopes they may have of pulling off what amounts to a mission impossible in London next week.

In fact, the Gunners legend reckons Tony Mowbray's men will be lucky not to suffer a heavier defeat at the hands of Arsene Wenger's superstar side than was meted out in the first-leg at Parkhead.

A 2-0 defeat at home has left Celtic seriously up against it to recue their Champions League dreams and a crack at the Europa League appears far more realistic than a miraculous recovery to reach the group stage of Uefa's flagship competition.

The Hoops players are trying to remain optimistic as they prepare to head down to London at the start of the week by insisting one goal could turn the tie on its head and perhaps spark an Arsenal collapse.

But Merson is adamant there is no chance of his former club suffering a disastrous result in front of their own supporters.

"It's all over," was Merson's matter-of-fact answer when asked if there was any way back for Celtic. "It is definitely all over. There is no way whatsoever that Celtic are going to recover from a 2-0 defeat in the first-leg.

"For Celtic to qualify for the Champions League they'd have to come down to the Emirates and win 3-0 - that just isn't going to happen.

"When is the last time a team won by that margin at the Emirates? I can't remember if I'm being honest.

"If Celtic were to have any chance of knocking Arsenal out of the competition then I feel they had to either win the first-leg at home or at least draw 0-0. If they achieved that then things would have been so different.

"For example, if Celtic kept a clean sheet then the tie would still be alive even if Arsenal went into a one-goal lead. It would have made for an extremely anxious night for the Arsenal players and supporters.

"And when there is so much at stake, mistakes can happen. But that danger no longer exists after Arsenal managed to go to Glasgow and win 2-0. They basically got the job done inside 90 minutes."

Merson always fancied Arsenal to see off Celtic. However, the former England international says Arsene Wenger's side haven't received enough credit for winning at Celtic Park.

He said: "You only have to look at Celtic's record in Europe to realise just how big a result it was for Arsenal to go there and win. It's over 25 years since an English team has gone there and won. That's a remarkable record.

"Better teams than this present Arsenal side, such as Manchester United and possibly even Liverpool, have gone there and failed to win.

"Down in England, people might look at the scoreline and shrug their shoulders and say they expected that to be the case. But as I said, look at the teams who have gone there and haven't won."

Despite having such a fantastic home record in Europe, Merson says there is a huge difference between the two teams in terms of the level they are operating at and what their goals are.

"On Tuesday night at Parkhead you had a team that was trying to simply qualify for the group stage of the competition and you also had a team that genuinely believes they can win the competition," said Merson. "That's the difference right there.

"Celtic would love to simply reach the group stage and it would help them out greatly in a financial sense and, as they've proved on a couple of occasions, they can manage to reach the last 16.

"But Arsenal are in the competition to win it. They've reached the final and semi-final in recent years. Can they actually go all the way and win it this season? Yes, if they keep their best 11 out on the pitch.

"Arsenal's problem is that they don't have as much strength and depth as some of the other leading clubs. On their day, however, they can beat anyone."

Merson was slightly disappointed at Tuesday night's Battle of Britain as he thought both sides failed to hit top form. But he reckons chasing the game could result in big trouble for Celtic this week.

He said: "I thought Arsenal were always comfortable without turning it on at Celtic Park. There was a degree of fortune with one goal a deflection and the other an own-goal.

"But the problem for Celtic is that they now have to go for it on Wednesday night and open up. And Arsenal aren't the sort of team to go through the motions. If a team is there to be punished, then they will punish you."

He added: "Look at the results last weekend. Both teams were three goals up but Celtic took their foot off the gas against Aberdeen and Arsenal go on to score another three goals away to Everton.

"So that could turn out to be a problem for Celtic. I'm looking forward to the game and hopefully both teams will perform better, but Celtic to turn the tie around? There is no chance of that happening."