Now the Parkhead club must negotiate an extra qualifying stage this year, with either Torshavn of the Faroe Islands or Lithuanian club Kaunas standing in their way.

But Lambert believes the physical game, which dominated their last match against Manchester United last summer, will stand the team in good stead after this week’s friendly in Seattle ahead of the game against Boca Juniors on Friday.

Lambert said: “We need games to test us, especially with the first Euro qualifier coming up.

“We must earn the right to be in the group stages and if we play the way we can then we should make it.

“We certainly don’t want another disappointment along the lines of what happened against Basle last season.”

But even the most ardent Celtic supporter was shocked by the involvement of Lambert in an incident at Old Trafford last summer.

The genial Scotland international became embroiled with Chris Sutton, Neil Lennon, David Beckham and the irrepressible Roy Keane following a clash between the Parkhead striker and the now-Real Madrid man.

Lambert added: “I’ve played against United four times, twice each with Celtic and Borussia Dortmund.

“Dortmund won 1-0 home and away in the Champions League and we beat them 4-3 down there in the game for Giggs.

“Before that they came to Parkhead for Tom Boyd’s testimonial match and we lost 2-0.

“United really got stuck into us that night and didn’t hold back.

“So we knew going to Old Trafford would be tough and we had to be really up for it.

“As usual it was a full house and you just don’t play friendlies when the stadium is packed.

“It never felt like a friendship game and it will be the same in Seattle.

“I was involved in an incident at the corner flag with David Beckham.

“There was a bit of a square-up but you have to expect that kind of thing when the adrenaline is flowing and you are pumped up.

“The ref stepped in to break it up. It was just one of those things.

“It can be hard to keep your cool all the time, especially when the fans are noisy and the place is heaving.

“Boca will also be determined to beat us and will be physically tough.

“Like the Germans, Argentinians are strong and I expect most of their players will be six feet plus.

“But it’s better to have matches like that rather than ones we’re going to win six or seven-nil.”