Premier League champions Arsenal face the embarrassing prospect of being dumped out of the Champions League at the first round stage this week. Placed second in Group E, they fact face bottom side Rosenborg of Norway at Highbury tomorrow knowing a win will put them into the knockout stages. And defending champs Porto have a real tough task of putting it across in front of a home crowd against the high-flying coach Jose Mourniho’s side. Here, we take a look at how the teams are placed before Tuesday night games.Group EArsenal vs Rosenborg TrondheimArsenal will advance to the knockout phase of the 2004/05 UEFA Champions League with a home win against Rosenborg BK, but having drawn their last four games in the competition, Gunners need to regain their winning touch against a side already eliminated from the competition if they are to be guaranteed a place in the last 16. PSV Eindhoven, on the other hand, have qualified with 10 points and they must travel to Greece to face a Panathinaikos side on six points, one behind Arsenal.Group FCeltic vs AC MilanCeltic, normally reliable at home, lost their opening match at Parkhead to FC Barcelona, a result that caused the Glasgow club to lose their way in this season’s competition. However, a gritty draw in the return match at the Camp Nou has given Martin O’Neill’s side a chance of advancing to the UEFA Cup. One point ahead of FC Shakhtar Donetsk, who host the already-qualified Barca, means that Celtic may need maximum points against AC Milan, who have also already confirmed their place in the knockout phase.Group GValencia vs Werder BremenAlthough Werder Bremen recorded a 2-1 victory against Valencia at the Weserstadion, the Spanish side will be hoping to make home advantage pay and deny their opponents a place in the knockout phase. History favours Valencia as Bremen’s three trips to Spain to date have all ended in defeat and ultimately elimination from or losses in European club competitions. The other match will be between Inter Milan and Anderlecht.Group HChelsea vs FC PortoIf the defending champions are to qualify for the knockout phase, they need to stop rampaging Chelsea at home with coach Jose Mourinho in charge. Hence Chelsea’s meeting with Porto on Wednesday night will be watched with all keenness. But as for Paris Saint-Germain, who are currently ranked in second place level on points with Porto, the head-to-head record favours the French side. With PSG hosting fourth-placed CSKA Moscow on the final matchday, a draw is not sufficient for the current European Champion Clubs’ Cup holders to retain their interest in this season’s competition.