Raheem Sterling scored the only goal as Manchester City beat Southampton to move right behind them in the table.
City took the lead after 16 minutes when Sterling converted Kevin De Bruyne's pull-back for his fourth league goal of the season.
Southampton responded well, with Theo Walcott and Jannik Vestergaard having the best of several first-half chances, but they could not beat Ederson.
The hosts were hit by the early departure with a hamstring injury of leading scorer Danny Ings and, despite second-half pressure, could not find an equaliser.
Having extended their unbeaten run to five matches, City sit sixth with 23 points.
Southampton are a point and a place ahead, having played a match more.
See: Southampton report | Man City report
Next fixtures
Southampton: 26 Dec v Fulham (A)
Man City: 26 Dec v Newcastle (H)
Referee: Mike Dean. Assistants: Ian Hussin, Darren Cann. Fourth official: Robert Jones. VAR: Lee Mason. Assistant VAR: Adrian Holmes.
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