|Champions League 3rd qualifying round, 1st leg|
|Venue: Pepsi Arena, Warsaw. Date: 30 July. Kick-off: 19:45 BST.|
|Coverage: Listen on BBC Radio Scotland 92-95FM, live text commentary on BBC Sport website.|
Expectation is stalking both Legia Warsaw and Celtic.
The two clubs need to reach the group stages of the Champions League to satisfy the demands for achievement on a wider scale than domestic triumphs.
Pressure will be in close attendance when the two sides meet in the third qualifying round, but it is the Polish club that is more susceptible to its harshest influence.
Legia Warsaw won the title emphatically last season, but that has provided no protection for manager Henning Berg.
He was brought to the club to succeed Jan Urban as manager in January because the team had failed in Europe; a priority that was underlined by the fact that Legia were top of the Polish top flight table at the time.
Berg is a manager with limited experience, but he was able to bring improvement to a team that was already effective. They won 12 of their last 16 games, and claimed the title by 10 points from Lech Poznan, yet criticism has crowded in on Berg in recent weeks.
Results alone portray a team that has yet to find its rhythm or its self-assurance, and the manager has been left exposed by the uncertainty of his side's displays.
It is early in the season, and Legia have played only five competitive matches, but there has been no hesitancy in poring over Berg's work.
Defeat by Zawisza Bydgoszcz in the Super Cup final was a set-back, although the Norwegian did not select his strongest side for the game.
A 1-1 draw at home to St Patrick's in the Champions League second qualifying round first leg led to Berg and his players booed off the pitch, and losing at home to GKS Belchatow in the opening league game of the season only exacerbated the sense of a team at odds with itself.
St Pat's were defeated 5-0 in the second leg in Dublin - with four goals coming late on after the Irish side had been left weakened in defence - and Cracovia Krakow were beaten 3-1 in Legia's league game preceding Wednesday's first leg against Celtic, but Berg remains a manager who is surrounded by doubts.
|Beat St Patrick's 6-1 on aggregate in second qualifying round||Beat KR Reykjavik 5-0 on aggregate in second qualifying round|
|Two games in to domestic league season||Yet to play a competitive domestic fixture|
|Featured in Europa League group stages last season||Reached Champions League group stages last season|
The assessments might in part be a consequence of misgivings that were raised at the time of his appointment, since his managerial career encompassed a three-year spell at Lyn, two years with Lillestrom and 57 days at Blackburn Rovers.
Legia Warsaw would not claim to be one of Europe's leading clubs, but some followers still questioned Berg's credentials for the role when the focus is on making progress in the Champions League. The Norwegian, after all, only had to quit his role as an occasional scout for Norwich City to take up the position.
The concern is that Legia are under-performing, but also that an opportunity will be missed. It is 18 years since a Polish side last qualified for the group stages, and Legia are still smarting after their experiences last season, when Steaua Bucharest knocked them out of the Champions League play-off round.
"Champions League qualification was the goal set, and it will be a huge disappointment if it wasn't achieved again," said Ryan Hubbard, a Polish football writer.
"Celtic will be massive favourites for the game. Having not qualified for the Champions League since 1995-96, Legia can only look on in awe at their opponents' record in the competition.
"However that isn't to say that fans don't think that they can progress. They are aware that in order to reach the competition they will have to beat at least one good team.
"While a Champions League exit wouldn't necessarily put Berg's position under threat - especially having faced a club like Celtic - it would mean added pressure to at least do well in the Europa League."
Legia are financially sound - they recently signed commercial deals with Pepsi and a telecommunications firm - which allowed them to strengthen the squad during the summer, and stave off interest in their own young burgeoning talents.
They signed two full-backs, in Igor Lewczuk and the Brazilian Ronan, while striker Arkadiusz Piech joined after scoring 14 goals in the league last season.
The recruits have added depth to a side that could already call upon Dusan Kuciak, voted the Ekstraklasa's best goalkeeper last season, and Serbian winger Miroslav Radovic, who was the player of the year.
Michal Zyro and Jakub Kosecki are the two youth graduates who have been attracting the most attention from the scouts of foreign clubs, and the former in particular is a dangerous attacking threat on the flank.
Berg, who won three Premier League titles in England and played at two World Cups, has been downplaying his side's chances by remarking that Celtic "are a step above where we are at the moment". However, psychology alone will not redeem him.
The former Manchester United and Blackburn Rovers defender was expected to bring European nous to Legia, because his playing career took him to the game's elite level, and to live up to that expectation he needs to solve the problems that have beset his team this season.