Chelsea substitute Pedro headed in an extra-time victor to see off Leicester City and put the visitors into their second successive FA Cup semi-final.
Alvaro Morata's first goal since Boxing Day on his return to the Chelsea starting line-up put the visitors on course to bounce back from their Champions League elimination at the hands of Barcelona in midweek.
Chelsea are now left fighting on two fronts in the remaining weeks of the season, as they attempt to lift the FA Cup for a fifth time in 11 years, while also finishing in the top four of the Premier League.
"It was a tough game but we knew this". "Don't forget, in the last game at home we chose to take this decision because he was very, very exhausted". "We must be pleased today".
'He played a good game, ' Conte said after seeing his side reach the semi-finals of the competition.
"When you arrive at this point, every game is hard". He was exhausted after a game like Barcelona, when we expended a lot of energy. Southampton have just changed coach but now it is important to be happy and to go for another game at Wembley. We also have to thank our fans. "I think this goal will be very important for the future for us". They continue to work hard and to make progress on the pitch, collectively and individually, tactically and technically. If you can win a trophy it is important for a team like Chelsea.
Puel felt his side deserved more from an entertaining encounter, adding: "I'm a bit upset at the moment because I think we deserved another result".