Chelsea rested Eden Hazard and Diego Costa for the match at Wembley Stadium, but had to bring them on in the second half, as they ultimately ran out 4-2 winners on the day.
Hazard scored a decisive third goal while Chelsea were under pressure from Spurs and Fabregas believes his boss was right to take the risk with Southampton so close, but he also thinks that their rivals will bounce back from defeat.
"I don’t believe so [win gives Chelsea a title boost], I am sorry," Fabregas said at Wembley Stadium. "It is a different competition and one day you can go to the final and the most important game for us, is still Tuesday.
"Getting to the final, is a big game, a big stadium and fantastic for the fans and everyone but the most important game is Tuesday and we have to keep it up. To get to another final, it is not easy to do nowadays, it is very competitive.
"Especially this Spurs side. They are very very strong and we have to be happy today. It is a happy day. I think during the season, this is a different season, a special season."
"This is the first time Chelsea is not in Europe for a long time and maybe it has been a little bit of an advantage in this case because we didn’t have to rotate as much and he played a lot with the same team this season but you see today, you know, Ake came in and played very very well."
"The last time he played was, I don’t know [a long time ago]. Maybe two months ago, Batshuayi the same. Willian didn’t start for the last five games and scores two goals so to have these kinds of players and then when we were struggling in the second half - we brought on these kind of big players and it worked very well today."