The champions are 11 points adrift of leaders Manchester City ahead of their trip to West Ham on Saturday, which comes before Manchester derby on Sunday.
Azpilicueta: Chelsea must win to keep pressure on Manchester clubs in the Premier League
Chelsea must beat West Ham United in the Premier League on Saturday to capitalise on points dropped by rivals in Sunday's Manchester derby, defender Cesar Azpilicueta said.
Champions Chelsea, who are 11 points behind leaders Manchester City, could go level with second-placed Manchester United with a win at West Ham's London Stadium in the lunchtime kickoff.
"The two (Manchester) teams can't both take three points, so every time you get an opportunity to get close, you have to take it," Azpilicueta told Sky Sports.
"We have to be intelligent to look at ourselves and then we'll see how the opponents will react."
After a sloppy start to the season, Antonio Conte's Chelsea have collected six wins in last seven league games, with their only dropped points coming against Liverpool in a 1-1 draw at Anfield last month.
The festive fixture list looks a good chance for Chelsea to collect a healthy points haul as they are set to face opponents outside the top six in their next six league matches.
West Ham are second from bottom and have not won in their last eight league games.
"We have to go game by game in this busy period in December - every three days you are fighting for a big three points. We have to look at ourselves," Azpilicueta added.
"We will then see where we are in the final weeks of the season, where we could fight for it."