Pep Guardiola's City bounced back from 0-2 to win 3-2 against Aston Villa.
Jarrod Bowen had scored twice in the first half to give West Ham a 2-0 lead.
Pep Guardiola's side crushed Newcastle 5-0 at the Etihad Stadium.
The Reds hung on to beat Manchester City 3-2 at Wembley Stadium to reach the final of the FA Cup.
Liverpool equalised twice in the 2-2 draw as the two sides remain separated by just a point in the table.
City have 69 points from 28 games with Liverpool on 63 from one game less. United slip down to fifth place.
City stretched their unbeaten run to 14 league games, pulling further clear of second-placed Liverpool.
Chelsea proved far too strong for Newcastle United as Reece James struck twice to fire the Premier League leaders to a 3-0 win at St James' Park.
Kevin De Bruyne scored in the 81st minute to make it 2-2 and give City a point at Anfield.
City were dominant against PSG, who lost their heads in the second half and finished the semifinal second leg with 10 men after Angel Di Maria was sent off in the 69th minute.