PARIS (AFP) - Jose Mourinho's Chelsea host FC Porto, whom he led to the Champions League title last season, with the self-confident Portuguese handler saying there is no room for emotional links in football.
The charismatic Portuguese, criticised for Chelsea's lack of goals but praised for defensive rigour, said professionalism had to come before nostalgia.
English champions Arsenal visit Norway's Rosenborg, AC Milan host Celtic and Barcelona entertain Ukrainians Shakhtar Donetsk on a night when Mourinho is determined to put feelings aside and get down to business.
"In football you have to be professional and forget these emotional links," he said. "For me, it's just a match I want to win - simply because if we have six points from two games then we almost have both feet in the second round of the Champions League.
"There are a lot of players there who are my players but there are no friends in football during 90 minutes - I want to win, they want to win. It is just one more match, no more than that."
Chelsea opened their Group H campaign with a 3-0 victory over Paris Saint Germain while Porto were held at home to a disappointing 0-0 draw by CSKA Moscow.
Paris Saint Germain visit CSKA Moscow with the boost that they have finally earned a victory in the French league this season at their eighth attempt with a 1-0 victory at home to Strasbourg on Saturday.
Arsenal manager Arsene Wenger confirmed non-flying Dutchman Dennis Bergkamp would not be travelling to Norway for the Rosenborg clash but claimed he was not short of options.
"But theres Jose (Antonio Reyes) who can play up front and on the left," said Wenger on Arsenal's internet site. "Robin van Persie could be another option."
Wenger agreed it would be a big game to give Dutch striker van Persie his full debut but added: "He has the quality to play." Wenger also ruled out back-victim Gilberto for the trip and said French winger Roberto Pires, who has a foot injury, only had a small chance.
PSV Eindhoven, beaten 1-0 at Arsenal in their first match, have the chance to make amends at home to Greek side Panathinaikos.
AC Milan hardman Gennaro Gattuso will be rolling up his sleeves and gritting his teeth for their home Group F clash against Celtic.
The uncompromising midfielder knows what to expect having spent a season in Scotland with Celtic's arch rivals Rangers and is bracing himself for a real scrap at the San Siro.
"They are like 11 beasts, physically very strong and they will never give up," said the tough-tackling 26-year-old, who made 36 appearance for Rangers in the 1997-98 season.
The no-nonsense Italy international believes Celtic will get a helping hand from their travelling army of fans.
"Around 10,000 will come and they will be charged up. They'll sing for 90 minutes," he added.
While Milan beat Shaktar Donetsk in the Ukraine a fortnight ago, Celtic lost their opening Group F match at home to Barcelona, so the pressure is on for Martin O'Neill's men to get some points on the board.
Barcelona, unbeaten in the Spanish league after five matches and who beat Real Mallorca 3-1 on Sunday, host Shakhtar Donetsk in the other fixture in the group.
German champions Werder Bremen face a stern examination of their credentials on Wednesday when seasoned European campaigners Valencia visit the Weserstadion for the Group G clash.
Bremen tasted a 2-0 defeat in their opening group tie with Inter Milan and know a loss against Spanish champions Valencia would leave them with a mountain to climb.
Valencia lost coach Rafael Benitez to Liverpool in the close season but his replacement, Italian Claudio Ranieri, has guided the club to the top of the Spanish league with an unbeaten start.
Bremen manager Thomas Schaaf was delighted to see his team record a 4-1 win over VfL Bochum at the weekend claiming his charges needed a confidence boost before facing mighty Valencia.
"The match has given us some confidence and we will need that in abundance on Wednesday," said Schaaf.
Anderlecht, who lost 2-1 to Charleroi in the Belgian league on Friday, host Inter Milan in the other Group G match.