Antonio Conte believes his Chelsea side have passed a psychological test in moving seven points clear of Tottenham but still face a fight to the finish in the Premier League.
Diego Costa scored twice as the Blues beat Southampton 4-2 at Stamford Bridge on Tuesday night in their first Premier League game since the loss at Manchester United saw their lead cut to four points.
Tottenham, who Chelsea beat in last Saturday's FA Cup semi-final, play their game in hand on Wednesday at Crystal Palace.
Blues head coach Conte said: "We passed a big step, a big psychological step after the defeat against United.
"Against United we lost three points and then we had to prepare a semi-final against Tottenham and then another tough game in the league.
"I think that in that moment we have had a really important test, psychological test. Our answer was very good. For this reason I must be pleased.
"But we must think that this race is open. We are ready to fight until the end."
Chelsea's prospects of a double in Conte's first season in charge remain alive, with 12 points needed from the final five games to clinch the league title before the May 27 FA Cup final with Arsenal.
"Everyone feels a bit of pressure," Conte added.
"The players, the club, but also the fans, that want to try to win after this season that I think is incredible for us, above all after a bad season like last season.
"It's important to continue to stay together and to understand this moment and to be ready to push our team in the right way."
Costa ended a seven-match scoreless streak for Chelsea with goals at either end of the second half, taking his tally to 51 in 85 Premier League games.
Conte said: "For strikers it's very important to score. Goals are your life.
"I always said I'm very pleased with his commitment, his work for the team. I was always confident about him.
"Now he must continue."
Eden Hazard and Gary Cahill scored in the first half for Chelsea, while former Blues Oriol Romeu and Ryan Bertrand replied for Saints as Conte's men conceded for an 11th successive Premier League game.
Conte's frustration with his side's defending was evident when he kicked a medical bag in his technical area during the second half.
He said: "In this part of the season, we are totally involved in the game.
"In that moment I wanted to kick the ball and I took the bag as a ball, because sometimes I want to play.
"I know if I kick the ball then probably the referee sends me off."
This was Chelsea's first home game since it was announced that John Terry would be leaving in the summer following 22 years of service.
The club captain came off the substitutes' bench for his 714th appearance and first in the league since November.
Terry, who has won 14 major trophies at Chelsea, could finish the season lifting more silverware and received acclaim from the home faithful.
Conte said: "He knows my admiration for him. It will be a great loss next season to lose a player like this."
Southampton boss Claude Puel felt his side showed a marked improvement from their previous game 10 days ago in a 3-0 loss to Manchester City.
But the Frenchman rued the concession of goals at crucial periods in the game.
"It's a shame that with the quality of this game we conceded four goals tonight," Puel said.
"It was a better performance than against Manchester City. But we conceded the goals in bad moments, after five minutes, just before half-time, just after half-time. this made the difference.
"We played against a great team and against two great players tonight. Eden Hazard and Diego Costa played very well. They can be the difference."
Puel, Hazard's first boss at Lille, added: "I'm very angry with him tonight, of course. But he's a fantastic player. I'm happy for him."