Some astute tactical tinkering and the return to form of some key players has put Chelsea back in the Premier League title picture and helped interim manager Rafa Benitez in his quest to gain acceptance among the club's disgruntled fans.
After a stodgy start to Benitez's reign, Chelsea has won its last three league games to close within four points of second-place Manchester City, still with a game in hand.
Benitez is slowly putting his stamp on the team, with the decision to bring in Victor Moses as a hard-working right winger and move David Luiz from central defense to central midfield proving a roaring success and giving the side a more robust look to it. With an 8-0 win over Aston Villa and a 1-0 victory at Norwich, Chelsea has returned back-to-back clean sheets over the hectic Christmas period.
Seeing Spain internationals Fernando Torres and Juan Mata looking sharp in front of goal will also please Benitez ahead of Sunday's tough-looking match at fifth-place Everton, which is unbeaten in seven matches.
"He came with slightly different ideas - it's working so far, and hopefully it will continue," Chelsea goalkeeper Petr Cech said of Benitez.
That will be music to the ears of the Spanish coach, who faced a tough task to win over the squad and the Chelsea fans after coming in as the replacement to the popular Roberto Di Matteo last month.
The initial hostility and supporter unrest has been silenced somewhat, with the hammering of Villa last weekend disproving the theory that Benitez is solely a negative, defensive tactician. Four clean sheets in his six league matches in charge, however, is typical Benitez.
"We were conceding too many goals, playing really open," Cech said. "Suddenly, we are defending as a team much better - that is the key.
"Now we are back to our ways when we are difficult to score against . I think we need the whole team to defend."
City's 1-0 loss to Sunderland left the champions seven points behind Manchester United in the title race.
A third straight defeat at the Stadium of Light reinforced the widely held belief that Sunderland is City's bogey team and the same could be said of Everton for Chelsea.
The London club has lost on its last three visits to Goodison Park in the league and Everton won't be easy to beat this time around either, with David Moyes' team holding one of only two unbeaten home records in the division.
"We are certainly a developing team and have developed a lot over the last year or so," said Everton midfielder Leon Osman, one of the scorers in Wednesday's 2-1 win over Wigan.
"We are playing some good football and we tend to show that more when we play against the teams at the top end of the table."
Everton inflicted one of Man United's three league defeats this season and also drew 1-1 at Man City.
Chelsea welcomes back Brazil midfielder Ramires from injury but captain John Terry is still out as he recovers from a knee problem.
United will look to extend its unbeaten run to eight matches when it hosts West Bromwich at Old Trafford but will be without Wayne Rooney, who damaged knee ligaments in training this week and is out for up to three weeks.
That should ensure Javier Hernandez - the scorer of United's 90th-minute winner against Newcastle in a 4-3 victory on Wednesday - gets another chance up front alongside Robin van Persie.
"Every time Javier has played, he has contributed," Ferguson said. "He has got 10 goals now and that is despite not playing every week. He is a great example to anybody who wants to be a footballer."
United manager Alex Ferguson said Friday that winger Ashley Young and striker Danny Welbeck were also available after missing the Newcastle match.
City travels to Norwich, which won five games in a row at Carrow Road before losing to Chelsea, with the grip on its title slipping.
"Seven points is a significant amount, there's no doubt about it," City assistant manager David Platt said. "United are in the driving seat but there is half a season to go. I don't think it is insurmountable by any stretch of the imagination."
France internationals Samir Nasri and Gael Clichy could both return from injury for City.