Werner struck a crucial goal with the 3-1 win in the balance.
"I was very happy to score and help the team," said Werner to the club's website.
"In the first half it was the story of my whole Chelsea career in one game a little bit! It was obviously not so clear because it took the referee a while to make his decision. Maybe 50/50. We have to accept it, I had to accept it, and in the end I was happy I could score again and we won the game.
"It was a very important win after losing the last two. It was a very tough game for us because Southampton did very well.
"We were a bit lucky they conceded the red card. It opened up a lot of space for us. They made it very hard to create chances, but overall we were the better team."
Werner also declared: "We won this game with pressure on our shoulders.
"We had the mentality to win. In the last two games we faced very good teams. It was hard to create chances against those teams. We wanted to be back to our old strengths, and we were.
"When you win the Champions League and start the season winning nearly every game, you become under a little bit of pressure to win and win and win every game. We know we are a very strong team and we are hard to beat.
"The last games were not so easy for me because I didn't start so regularly.
"So it was not only important for me, it was important for the whole team to come back after two defeats before the national break, where we won't see each other for a week and a half.
"It was important for everybody to go to the national break with a good feeling. At big clubs you always feel pressure, but in the end you must have fun, and you saw we wanted to have fun, play football and win the game. That mentality makes us so strong."
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