Andre Villas-Boas has admitted he will have one eye on Chelsea's Barclays Premier League showdown at Manchester United when he picks his team for Tuesday night's Champions League opener against Bayer Leverkusen.

Villas-Boas is planning to make changes for the Group E clash at Stamford Bridge in the midst of his biggest week since taking charge of the Blues more than two months ago.

"You'll see some changes," said the 33-year-old, who must decide whether to recall Fernando Torres to his attack and who will replace the suspended Ramires in midfield.

"Then we'll make wise decisions for Sunday."

Didier Drogba will once again miss out on Tuesday night as he continues his recovery from a head injury.

The striker was given another two days off this week and is looking more and more likely to sit out Sunday's trip to Old Trafford.

Torres appeared a strong favourite to continue his run in the team before he lost his place for Saturday's win at Sunderland and the misfiring striker's misery deepened on Monday when it emerged Chelsea were probing an interview he gave in which he appeared to criticise his own team-mates.

The Spain forward claimed his comments were mistranslated, even though they appeared on his personal website.

Torres was bought to help Chelsea win the Champions League, with Villas-Boas ultimately recruited for the same reason.

The Portuguese has yet to manage in the competition but has plenty of experience of it from his time on Jose Mourinho's coaching staff.

History shows it can be vital for a team to win their group to go on and lift the trophy, but Villas-Boas said: "The competition is full of exceptions.

"I lived Porto's experience and we managed to play all the second legs away from home and still qualified to win the Champions League in 2004."

Tuesday night's game will reunite Villas-Boas and Chelsea with former Stamford Bridge midfielder Michael Ballack.

Villas-Boas said: "I haven't been able to speak to Michael for a lot of years, since I left.

"He's a player who represented a lot to us and represents a lot to Leverkusen.

"I'm not sure about the thoughts of their coach regarding Michael's inclusion in the squad, because they've been using him sometimes and other times not.

"But he adds value to the squad with the vision he has."

Ballack returned the compliment about the former Blues scout, who is a year younger than him.

The veteran midfielder said: "In my time at Chelsea I had a few coaches and sometimes they changed them maybe a little too quick, but what is surprising is he is a very young coach.

"When people talk about him, they talk most of the time about his age but he showed his quality when even in this young age he won a European trophy with Porto, which is unusual.

"It is not surprising that Chelsea always had their eye on him, he worked there before in the background and he did a lot of important stuff for Jose Mourinho."

Ballack has admitted he would forever be haunted by Chelsea's Champions League final loss to Manchester United but is ready to inflict more misery on his former club.

The 34-year-old has the unique honour of being the only man to play in the biggest game in both clubs' history, inspiring Leverkusen to the 2002 Champions League final before starting for Chelsea in the 2008 showpiece.

Unfortunately, the midfielder ended up on the losing side on both occasions, but it was perhaps the penalty shootout heartache in Moscow that was the more difficult defeat to take, with Ballack on Monday saying: "It will haunt all of us for ever."

Former Germany captain Ballack, who turns 35 this month, will receive a special presentation from Chelsea in recognition of his four years' service before kick-off on Tuesday night.

He said on Monday: "The presentation is a very nice gesture and it will be a very emotional moment for me tomorrow.

"There are still a few players there and some who left in the meantime who I am still friends with and whom I am still in touch with, and also a few of the staff.

"When I moved to Chelsea, it was a big, big challenge and experience for me at the time to play with so many good players.

"If I look back, I had a very good time. I feel always welcomed by the fans and the club. They treat me always very well and we had success.

"We missed a few chances, but we had some successes and I will remember this always and it is a big part of my career."

Bundesliga runners-up Leverkusen will be underdogs on Tuesday but Ballack said: "It is just a game of football, although we are aware there are some big names on the other side.

"We will have our chances."