Chelsea have already hatched plans to stop Manchester United's Cristiano Ronaldo from putting a further dent in their title ambitions.
Ronaldo is well known to Chelsea coach Luiz Felipe Scolari from his time as manager of Portugal and defenders Jose Bosingwa, Ricardo Carvalho and Paulo Ferreira, along with midfielder Deco, have all played along side the United winger for their national side.
Ronaldo is expected to play against Chelsea despite writing off his Ferrari in a crash near Manchester Airport earlier this week. The 23-year-old winger was driving his sports car through a tunnel beneath the runways when he lost control and smashed into a barrier.
But defender Bosingwa insists Chelsea already have plans in place to stop him from having a major effect on the game.
Bosingwa said: "To stop Cristiano is not easy but at Chelsea there are people who know him well, including the manager - we know what to do stop him.
"This week I have noticed a greater intensity in training at Chelsea.
"I have seen more energy in all my colleagues because we have a big match against United which is vital for the league title and we want to win it."
Chelsea's indifferent form has seen them slip three points behind leaders Liverpool at the Premier summit.
Chelsea dropped two valuable points away at Fulham when Clint Dempsey snatched a last-minute equaliser to add to Scolari's frustration.
A Liverpool victory over struggling Stoke and a defeat for Chelsea at Old Trafford could have severe implications for Scolari's chances of lifting the title in his first season in England.
But Bosingwa summed up Chelsea's determination to prove they are still very much title contenders.
"Some people are beginning to doubt our chances for the title but we want to leave Manchester proving that there is a lot still be to be decided," he said.
Scolari is boosted by the return of captain John Terry who has missed the last three games through suspension following his red card in the goalless draw at Everton.
"It is important for us that John is back because he is our captain and a man who has a good position on the pitch," said Scolari.
"He is a leader and plays very well every game. I think on Sunday the opposing players will respect him as well. I have five central defenders in very good condition and this is very good for me."
Scolari also believes the trip to Old Trafford is the perfect fixture to motivate his squad after the disappointment of their FA Cup third round draw against Southend.
"It is the perfect game to lift them all," said Scolari. "It is a fantastic game. I think half of the world will be watching this game.
"The players don't need any motivation. It is very good for us after Southend because it was not a normal result.
"We had 27 shots and scored one goal, they had three shots and scored one goal. This game is two very good teams who have fantastic players.
"We need to win because they are four points behind us and have two games in hand.
"Those two games are not against us. It is not in our hands and we need to think about winning this game.
"If you lose one game or three points against a direct opponent like United, you are in trouble.
"I think United are playing very well. They win many games, sometimes 1-0 but 1-0 is three points."