The Blues had to see off the Saints through a penalty shootout, same procedure they used to eliminate Aston Villa before meeting Southampton.
After taking the lead for Chelsea in the 44th minute, a Che Adams' tap-in levelled the score for Ralph Hasenhuttl’s men, taking the game into a penalty shootout.
However, Tuchel who was able to make some last-minute changes to team selection to defeat Southampton expressed his excitement for advancing to the next stage of the competition.
“We had some last-minute changes because three potential starters got injured in training so it was not planned like this and not so many options from the bench,” he said.
“We knew it was the first time we played together like this and things would be tough against a team who put so much pressure on you like Southampton and that was the way it was.
“It was a nice match of football, good performances by both teams and a tough match but in the end we win with a penalty shoot-out.
“Every competition is an important competition. We don’t want to judge what is more or less important.
“When you go out and wear the shirt and prepare matches we play all in. No matter what competition because this is what the club is all about and what the players want.
“There is no judging. Players get their chance and used it. The problem is we have another match now in December which is pretty full.”
