The prospect of Matildas Mary Fowler and Alanna Kennedy winning England Women's Super League has moved a step closer as their Manchester City team took advantage of Chelsea being engaged in Europe to move three points clear.
City also enhanced their goal difference, putting five past Mackenzie Arnold in the West Ham goal.
Two goals in Sunday's opening four minutes set City on their way, with Fowler and Kennedy both playing the full 90 minutes.
It was a less enjoyable day for Arnold, but she had little chance with the goals and made several good saves, including one from a Kennedy free-kick.
With three league games left to play City top the standings on 49 points, three ahead of Chelsea who have a game in hand, and six ahead of third-placed Arsenal.
Chelsea, who won their Champions League semi-final first leg in Barcelona 1-0 on Saturday, have a three-goal deficit on goal difference..
Leila Ouhabi netted in the first minute against West Ham, with Kadiga Shaw adding the first of a brace three minutes later.
Shaw struck again in the 24th minute and City added two more goals in the second half through Laura Blindkilde, set up by Fowler, and Jess Park.
In London, Caitlin Foord and Steph Catley both created goals as Arsenal beat Leicester City 3-0 to ensure they will be in next season's Champions League qualifiers.
In front of nearly 43,000 at the Emirates Foord set up Beth Mead for the first and Catley assisted Alessia Russo for the second, before Mead scored again.
Earlier on Sunday, Manchester United's Maya Le Tissier scored in the second minute of second-half stoppage time to grab a 2-2 draw at home to Tottenham Hotspur.
