Chelsea manager Antonio Conte said his side had taken "a big psychological step" after they defeated Southampton 4-2 to move seven points clear at the Premier League summit.
Chelsea's recent 2-0 loss at Manchester United allowed closest rivals Tottenham Hotspur to trim their advantage to four points.
But they beat Tottenham 4-2 in the FA Cup semi-finals on Saturday before overcoming Southampton by the same scoreline on Tuesday to turn up the heat on Spurs, who visit Crystal Palace on Wednesday.
"I think we passed a big, big step," Conte told reporters at Stamford Bridge.
"A big psychological step after the defeat against United. Because against United we lost three points and then you had to prepare (for) a semi-final against Tottenham.
"We reached the final in the FA Cup, which is a great incentive for us. But the other competition, the league, is totally open.
"But I think we are ready to fight until the end. Then we must be proud for our job, for what we are doing this season."
Diego Costa was Chelsea's match-winner against Southampton, scoring twice in the second half to take his Premier League tally to 51 goals in 85 appearances and end a seven-game scoring drought.
"It's normal for the strikers that it is important to score. The goals are their life," said Conte, whose side visit sixth-place Everton on Sunday.
"But, for me, I've always said I've been pleased with his commitment, his work for the team. He always worked for the team.
"Sometimes he was unlucky in different circumstances, but I was always confident about him. After the Tottenham game, I said I'm sure he's keeping his goals for the final weeks of the season.
"Now he must continue. He's very important for us. His confidence is very important for us. He scored two very beautiful goals, good combination and technique between him and his team-mates."
Chelsea took a fifth-minute lead on a chilly evening in west London when Cesc Fabregas's incisive pass found Costa, whose cut-back was swept home by Eden Hazard.
- Coup de grace -
Oriol Romeu, playing against his former club, levelled mid-way through the first half when he stabbed home Manolo Gabbiadini's cross-shot after Chelsea were found wanting at a corner.
But Gary Cahill restored Chelsea's lead in first-half stoppage time, bravely heading in N'Golo Kante's deep cross, before Costa took centre-stage in the second half.
He made it 3-1 eight minutes in, nodding in Fabregas's cross, and added a late coup de grace by drilling home after exchanging passes with Hazard and substitute Pedro.
Ryan Bertrand, another Chelsea old boy, claimed a consolation with a stoppage-time header.
Southampton had been beaten 3-0 by Manchester City in their previous game, 10 days prior, and have failed to record a league victory over any of the teams in the top six this season.
But manager Claude Puel, whose side remain ninth, drew encouragement from the moments of discomfort the visitors managed to cause Chelsea.
"It was a better performance than against Manchester City," said the Frenchman, whose team lost to Manchester United in the League Cup final earlier this year.
"But we conceded the goals in bad moments -- after five minutes, just before half-time, just after half-time. This made the difference."
Conte explained he had given club captain John Terry a late substitute cameo to "thank" him, following the centre-back's recent announcement that he will leave the club at the season's end.
Conte was typically animated on the touchline, at one point kicking a medical bag sitting beside the dug-out after Chelsea left Gabbiadini unmarked at a second-half corner.
"In this moment I wanted to kick the ball and I took the bag as a ball," the Italian explained.
"Sometimes, believe me, I want to play. I want to play, to kick the ball. But I know that if I kick the ball, the referee will probably send me off."