The atmosphere will be unusually tense at Chelsea’s Stamford Bridge stadium tomorrow when the Londoners take on Bayern Munich in the first leg of a Champions League quarterfinal. It’s a vital game, of course, but one that has been supercharged into a potentially explosive affair by the ongoing dogfight between Chelsea coach Jose Mourinho and UEFA.

The trouble started in the previous round, when Mourinho publicly accused the Barcelona coach, Frank Rijkaard, of making a half-time visit to referee Anders Frisk’s locker room during the first leg of the tie. After that visit, according to the Mourinho theory, Frisk’s refereeing turned anti-Chelsea in the second half. Frisk ejected Chelsea’s striker Didier Drogba, and Barcelona won the game.

Chelsea triumphed in the second leg and advanced to the quarterfinals, but Frisk found his home phone and e-mail bombarded with messages threatening himself and his family. So threatening, that Frisk – age 43 and at the height of his refereeing career – announced his retirement from the game.

Many of the callers, it was established, had London accents; they were logically assumed to be Chelsea supporters. From UEFA came a furious response, condemning Mourinho for what it saw as provocative statements. UEFA referee chief Volker Roth nailed Mourinho as “an enemy of soccer.” Mourinho threatened to sue, but UEFA then claimed that Roth’s statement had been mistranslated.

UEFA persisted, formally charging Mourinho with bringing the game into disrepute and making false declarations. While Chelsea pondered its response to the charges, Mourinho blithely tried to ease himself off the hook, admitting that he had not actually seen Rijkaard enter the referee’s locker room – he was relying on the word of two of his assistants.

UEFA was unimpressed with Mourinho’s evasive tactic and called a special hearing at its headquarters in Nyon, Switzerland. Chelsea sent three representatives, but Mourinho did not attend, nor did either of the two assistants who claimed to witness the locker room visit.

The absence of key figures hardly mattered. An earlier statement by UEFA’s chief executive, Lars-Christer Olsson, had revealed UEFA’s uncompromising mood: “We will not allow the slandering of match officials to become part of pre-match tactics. We must sanction anyone within the soccer family who makes inflammatory statements that could jeopardize the security of match officials and their families.”

After a three-hour session, UEFA imposed a $62,600 fine for Chelsea and a $16,700 punishment for Mourinho. These are derisory amounts for what are arguably the richest club and the best-paid coach (at a reported $7 million a year) in the soccer world. UEFA also added a two-game ban for Mourinho – another light punishment, only just above the minimum.

After the hearing, Chelsea’s president, Bruce Buck, was in a conciliatory mood, announcing that the club would probably not appeal the verdict, and wanted to put the incident behind it.

The usually talkative Mourinho, however, has not been heard from. His original claim of complicity between Rijkaard and Frisk was dismissed by UEFA, which preferred to listen to the accused parties and the sworn eyewitness testimony of two of its own observers at the game, who said that the alleged locker-room visit by Rijkaard never happened.

An apology – or at the very least an expression of regret – from Mourinho would seem to be called for. But the coach has remained silent. Which is exactly what he will have to be during both quarterfinal contests against Bayern Munich. The UEFA ruling forbids him any contact with his team at the stadiums. He will not be on the bench, nor will he be allowed any sort of telephone communication with his assistants, Steve Clarke and Baldemar Brito.

The games against Bayern Munich will not be easy for Chelsea. German clubs usually do well against their English counterparts, and Mourinho & Co. will be well aware that, in the previous round of the Champions League, Bayern knocked out Chelsea’s great London rival, Arsenal.

Both Chelsea and Bayern are facing injury problems. Claudio Pizarro, Bayern’s Peruvian striker – and scorer of two goals against Arsenal – was injured during Saturday’s Bundesliga game against VfL Wolfsburg, and will miss an estimated 12 days. His replacement will be another Peruvian, the 21-year-old Paolo Guerrero.

Also injured in the Wolfsburg game was Bayern’s top goal-scorer, Dutchman Roy Makaay, but coach Felix Magath is hopeful that he will be fit for Wednesday.

Chelsea’s injury woes arrived with last week’s batch of World Cup qualifying games. Defender Paolo Ferreira broke a bone in his foot playing for Portugal, and Dutch winger Arjen Robben hobbled out of the Netherlands-Armenia game with an ankle injury that may keep him sidelined for a month.

But the most obvious – certainly the most talked-about – absence for Chelsea will be that of Jose Mourinho. Like most modern coaches, Mourinho is a very noticeable presence during games. From within the designated “technical area” around the bench, Mourinho does his share of shouting, pointing, waving his arms, and generally giving the impression that he is controlling every move made by his players.

Whether all the theatrics are really necessary is questionable, and many feel that Chelsea will manage okay, even without Mourinho’s forceful presence on the game. Chelsea, after all, has the look of a smoothly operating, error-free team that ought to be able to operate efficiently on auto-pilot for a couple of games.

That would be a safe bet within the Premier League, where Chelsea holds a comfortable lead atop the standings. But European games, which bring unfamiliar playing and refereeing styles and more sophisticated tactics, are different. Over the past 20 years, English clubs have won the Champions League once (Manchester United in 1999) and the UEFA Cup once (Liverpool in 2001) – just two wins in 40 tournaments.

Mourinho is a European coach. He knows about European competition at the highest level, having won both the UEFA Cup (in 2003) and the Champions League last year with his former club, FC Porto. Indeed, one of the main reasons that Chelsea hired him was to exploit his European know-how.

Yet now, thanks largely to Mourinho’s own precipitate actions and his baiting of UEFA, that expensively acquired know-how will be missing from the Chelsea bench for the two vital games against Bayern Munich.