Manchester - While Europe's other big leagues take a breather over the festive period, clubs in the English Premier League begin a traditionally frenzied spell of fixtures that excites fans, exhausts players, tests managers, and potentially defines campaigns.
A run of four games in nine or 10 days kicks off on Friday with a full program, with Chelsea looking to tame one of the surprise teams of the season to stay in first place and keep title rival Manchester City at arm's length.
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West Ham arrives at Stamford Bridge in fourth place and as London's No. 2 team this season, a side reborn under Sam Allardyce following summer orders from the hierarchy to play a more attractive brand of football.
West Ham is certainly doing that and impressive wins over City and Liverpool so far suggest a trip to Chelsea will hold no fear.
"Playing against Big Sam (Allardyce) is a hard job for us, we have to cope with it," said Chelsea manager Jose Mourinho, who thinks his team has the hardest festive fixtures of all of the top teams with games at Southampton and Tottenham to come.
By beating Stoke on Monday, Chelsea restored a three-point lead over City and ensured it would be top on Christmas Day a noteworthy milestone that has special significance for the Blues. The last three times Chelsea has led the league on Dec. 25, it has gone on to win the title.
"What we did in the past is not important," Mourinho said. "What's important is this season, and this season we are top of the league since day one and we are there because we are playing really well.
"In my opinion we are the best team."
Here are some other things to look out for in the 18th round:
Exciting West Ham: When West Ham last travelled to Chelsea, in January 2014, the visitors held on for 0-0 despite conceding 39 shots on their goal, and were accused by Mourinho of playing "football from the 19th century" because of their defensive tactics.
That is unlikely to be the case this time round, with Allardyce recently speaking of his "fantastic options" up front with strikers Andy Carroll, Diafro Sakho, and Enner Valencia, and attacking midfielder Stewart Downing looking sharp.
"We're playing great football, and any team that we play against is going to be worried about us," said Carroll, who has rediscovered his best form after injury. "We've got more than one attacking option - we play it on the floor, play it in the air, down the sides."
West Ham hasn't been in a higher position in the top flight of English football at Christmas Day since 1985.
No Strikers for City: Man City manager Manuel Pellegrini is facing the unenviable task of negotiating the festive period without any strikers.
Sergio Aguero, Edin Dzeko and Stevan Jovetic will again be missing when City plays away at West Bromwich Albion. City coped on Saturday against Crystal Palace, playing midfielder James Milner up front and winning 3-0.
Pellegrini said Dzeko and Aguero are unlikely to return until "the second part of January" but Jovetic will be sooner.
City has won its last six league games in the defense of its title.
Van Gaal's treat: Louis van Gaal is breaking with tradition at Manchester United and giving his squad Christmas Day off.
Players used to train on Christmas Day under long-time coach Alex Ferguson, and did so in David Moyes' short tenure last season, too. Van Gaal is dealing with English football's unique festive fixture schedule for the first time, and sees things differently.
"I believe in a total human being, so the environment is also important," the Dutchman said ahead of United's home match against Newcastle. "They are more pleased to be at home with their wives and children."
Leicester worry: Since the Premier League's inception in 1992, only two teams have stayed up when bottom of the standings at Christmas. The omens, therefore, are not looking good for Leicester.
Leicester is winless in 12 games, five points from safety, and its manager Nigel Pearson is one of the favorites to become the first Premier League coach to be fired this season.
Leicester is at home to Tottenham on Friday.