The Chelsea boss was furious after seeing his side's title chances suffer a setback with a 2-1 defeat at the Hawthorns and he his planning to make changes for the next two games.
The Blues face a crucial showdown with Juventus in the Champions League as their qualification hangs in the balance, while a clash against Premier League champions Manchester City is also on the horizon.
Di Matteo is ready to go back to basics in order to tighten up at the back and also hinted he needs a new striker that can score goals.
"It's time to change in terms of set-up and selection because we need to go back to winning games and not conceding goals," Di Matteo revealed.
"We have to sacrifice a bit of our attacking options and go a bit more defensive to make sure that, first and foremost, we don't concede.
"The pressure is always there and it doesn't help when you don't win. Giving away goals like we did today makes it very difficult to do that.
"Our defending was very poor today and we have to do better. For three years running this team has had a dip in November and for some reason we're back in this position again.
"We have two massive games coming up and we have players who have experience of being in this position before. Sometimes you need to be able to win 1-0 and focus on responsible defending to bring the points home.
"We also need the strikers to chip in with more goals because that is what they are there for."