Jose Mourinho successfully altered the team shape on Saturday with Chelsea running out 3-0 winners at West Ham, but he explains changes are being made on a game-by-game basis rather than there being an enduring formation change.

Having lined the team up in a 4-2-3-1 for most of the season, the shape at Upton Park was more like the one used throughout most of his first period at the club - 4-3-3 with an anchor midfielder, two more central midfielders pushing forward and two wingers.

This weekend John Mikel Obi's presence allowed Frank Lampard and Ramires freedom to attack more than previous games, with Oscar on the right and Eden Hazard on the left the wide players.

'It worked because West Ham have a certain style of play and it was very important to cope with the first long ball and with the second ball,' Mourinho says.

'When you lose the first ball you are in trouble behind, and when you lose the second ball you are in trouble controlling the game, so we tried to put more people in that area, the three midfielders plus Oscar coming to the middle too, trying to get the second ball. Then when you have the second ball you play.'

The two-week international break denied the manager much time to work with his players but it allowed him to study every West Ham game this season, a time-consuming process not always possible when the team are playing a game every three or four days. Such studying allows specific game plans to be carefully developed. Mourinho indicates the formation may switch back again but praises the contribution Mikel, who was the one change to the team on Saturday, can make.

'Mikel plays the same way today as he was playing when he was 18 - position, stability, control, to score a goal is a miracle but also to lose the ball is a miracle, so in some matches he is very important.'

The next test for the team and Mourinho's planning is Basel away where one point won will be enough to qualify for the knockout stage and three will win the group.

'We are going to try to win and kill it,' he says. 'We have so many crucial matches in December that if we can have one less and the one less is Steaua then it will be a help.'

- Jose Mourinho's post-match interview with Chelsea TV is available now via the channel's online access.