Manchester City beat Crystal Palace 3-0 to move level with English Premier League football leaders Chelsea, while West Ham closed in on third-placed Manchester United, who were held to a 1-1 draw at Aston Villa.
City were missing Sergio Aguero, Edin Dzeko and Stevan Jovetic due to injury, but they secured an eighth consecutive win in all competitions thanks to David Silva's second-half brace and a late Yaya Toure strike.
Victory left City level on 39 points with Chelsea, who remain top by virtue of a superior goal difference (+23 to +22) ahead of their trip to Stoke City on Tuesday.
"It was a very good win. A very good performance. I enjoyed the way the team worked the whole week - to work in a different way without strikers," says City manager Manuel Pellegrini.
"I did think December is a key month to be in the fight for the title, and if you want to be involved you must be very near the top of the table. I hope we continue playing like this."
United spurned a chance to close on Chelsea after dropping points for the first time in seven matches at Villa, who had Gabriel Agbonlahor sent off in the 65th minute for a foul on former team-mate Ashley Young.
The draw ended United's run of six straight wins and left Louis van Gaal's side seven points off the pace in third place, while West Ham United, Southampton and Tottenham Hotspur all closed on them.
Radamel Falcao scored for Manchester United.
"Very frustrating. I think we gave two points away," says United manager Van Gaal.
"I'm disappointed because also in the first half we were the better team and when that's the case, you have to win."
All White Winston Reid's fourth-placed West Ham are now just a point behind United after beating bottom club Leicester City 2-0 at Upton Park.
Andy Carroll seized on West Ham old boy Paul Konchesky's disastrous back-pass to put the hosts ahead in the 24th minute and Stewart Downing made it 2-0 11 minutes after the interval with an stunning 25-yard effort.
Southampton are two points further back after ending a five-game losing streak by beating Everton 3-0 thanks to a Romelu Lukaku own goal and second-half efforts from Graziano Pelle and Maya Yoshida.
Tottenham beat Burnley 2-1 to leapfrog Arsenal, only for the Gunners to go back above Spurs with their 2-2 draw at Liverpool on Monday.
Charlie Austin took his tally for the season to 11 goals with a hat-trick as Queens Park Rangers came from 2-0 down to win 3-2 at home to West Bromwich Albion, who scored through Joleon Lescott and Silvestre Varela.
The win took QPR out of the relegation zone, but Hull City remain in the bottom three after Jonjo Shelvey's shot deflected in off Ki Sung-yueng to earn Swansea City a 1-0 victory at the KC Stadium.