Jose Mourinho revealed Oscar admitted diving in a failed attempt to win a penalty and get Southampton goalkeeper Kelvin Davis sent off in Chelsea's 3-0 win at St Mary's.
Brazil midfielder Oscar had only been on the pitch for a matter of seconds after replacing Juan Mata when he went into the book for his theatrics and Blues manager Mourinho made it clear he thought referee Martin Atkinson had made the right decision.
Oscar then went on to set up Fernando Torres for Chelsea's first goal and scored the third himself after fellow Brazilian Willian had made it 2-0.
Asked about Oscar's dive, Mourinho added: "It was a fair yellow card. I don't like it but his explanation to me I also accept.
"He said to me; 'when I saw the goalkeeper coming I was thinking 'penalty, red card, goodbye' and the goalkeeper - he is a 35 or 36-year-old man (Davis is 37) with lots of experience - thought 'I am going to stop'.
"Oscar found himself in a moment of contradiction - and we are speaking about fractions of a second - where he thinks 'contact, penalty, red card' and there was certainly no contact.
"Oscar is a clean player who was waiting for the goalkeeper to come and smash him because that's what normally happens in those situations."
Mourinho was quick to praise Oscar for the more acceptable side of his game as the Brazilian put Chelsea firmly in control of what had been a tough test before his 53rd-minute arrival as a substitute.
"Oscar and Willian changed the game," Mourinho said. "They came on and gave a different intensity to the game. We scored and after that it was our dominance even more.
"We finished the game in a comfortable way and we really deserved the victory."
Mourinho also opted against criticising Mata, who reacted angrily after making way for Oscar -- a show of dissent that will inevitably intensify speculation that the Spanish midfielder could be leaving this month, with a number of sides from his home country keen to sign him.
Mourinho insisted however that any move would not be instigated by him. "I want to keep him," he said.
"I don't want him to go. That is my opinion, my wish. But my door is open. The club's door is open too so when a player wants to speak to us we are there waiting for them."
Mourinho also played down Mata's reaction to being substituted.
"I think it's frustration about the result because we knew we had to win," he said.
"If we didn't the difference to the leaders is bigger and when he came out of the team we were losing two points.
"So I think his frustration is about that because at the conclusion of the game, everybody - including him - was celebrating the victory in the dressing room."
Southampton have now won just one of their last nine games, although they still find themselves in the Premier League top 10 following an excellent start to the season.
Head coach Mauricio Pochettino admitted his main task this month was to make sure his best players remained at the club, with midfielder Adam Lallana having broken into the England team and young left-back Luke Shaw being linked with Chelsea and Manchester United.
Pochettino, who insisted he knew nothing about a move by West Ham for England forward Rickie Lambert, said: "It is important to keep the best players but also to recover the injured players and to perform as a unit."