Jose Mourinho said a first-half booking for Michael Essien was part of his reason for withdrawing the Chelsea midfielder during the 3-1 win against Southampton.
A woeful mistake by Essien, making his first Premier League start of the season, led to Jay Rodriguez scoring for the Saints after only 13 seconds at Stamford Bridge.
Mourinho replaced Oscar, who had picked up a knock, with Frank Lampard shortly before the interval and then with Chelsea trailing at half-time he sent striker Demba Ba on in place of Essien.
“Essien had a yellow card against him and was playing in a crucial part of the pitch,” Mourinho explained.
“We changed to 4-4-2 and that gave Southampton a different game that they didn’t expect.
“We were losing and not producing enough and my feeling was not to wait, but to try immediately to give the opponent a new problem.
“Southampton like to build from the back and with two strikers pressing them it enabled my team to play more in the opposing half and create chances.”
Mourinho, who added that he was unsure what Oscar’s injury is, praised his team for a second-half fightback in which goals from Gary Cahill, John Terry and Ba gave them a deserved victory.
“The [Southampton] goal was like a knife in the back but I think in the first half we played very well,” said the Blues boss.
“We played with balance, were calm with no panic and no silly mistakes, not risking a lot and not going 2-0 down.
“It was a good performance collectively and there were some good individual performances. We deserved the three points.
“It was the sign of a team going step by step, understanding my ideas and mentality, and players progressively adapting.”