Sir Alex Ferguson may attempt to dazzle his old rival Rafael Benítez into tactical submission by reconfiguring Manchester United into a diamond formation for Sunday's FA Cup quarter-final against Chelsea at Old Trafford.

There is no love lost between the two managers and Ferguson is anxious to ensure Benítez returns to London a beaten man. "I just need to make sure I pick the right team, bearing in mind who our opponents are," said the Scot, who seems anxious to accommodate both Wayne Rooney and Shinji Kagawa in his starting XI.

"Wazza and Shinji can play together, there's no doubt about that," said Ferguson. "At Newcastle [when United won 3-0 in October] we played a diamond and that's a consideration. We played Wazza centre midfield and Shinji towards the right. They did really well in that game. Good footballers can play together. I think the preferred position for Shinji is off the front man in a central position and that's the same for Wazza. We maybe have to alternate them."

Rooney and Kagawa were omitted from United's starting line-up for Tuesday's Champions League defeat against Real Madrid but they combined well as Ferguson made a rare shift from 4-2-3-1 to 4-3-3 for last Saturday's 4-0 home win over Norwich. Kagawa scored a hat-trick from midfield, while Rooney, operating in the front three, scored one and created two goals.

Ferguson is also mindful that Robin van Persie is keeping Javier Hernández out of United's attack. "Chicharito's record against Chelsea is unbelievable," he said. "I have these issues. The form that Van Persie is in is strong and we've had to leave Chicharito out because of Van Persie. It's not easy. Sunday's a big game, I think Van Persie will want to play. But Chicharito's scored 15 goals and every time he comes in he does a job. You can't keep knocking him down all the time. It's disappointing to leave good players out of your team."

In central defence Ferguson knows three will not go into two and he must decide who to omit from Nemanja Vidic, Rio Ferdinand and Jonny Evans. "The combination of Vidic and Ferdinand was fantastic against Madrid," he said. "But I do need to decide whether to bring in Evans. Jonny has probably been our best defender all season. You have to analyse the team for strength."