The Hammers are flying high in third place in the Premier League after a fantastic start to the campaign and have racked up a perfect record in derbies with their latest capital win over Chelsea on Saturday.
And that success has been built on Slaven Bilic's ability to get his side up for big games against London rivals with the Hammers winning all three of their derby matches so far.
The perfect start to season of derbies
Who can forget the first, that surprisingly comfortable 2-0 victory over Arsenal at the Emirates on the opening weekend which set the ball rolling on what has been a memorable season so far.
Then came the recent 3-1 away win over fellow strong starters Crystal Palace before Saturday's meltdown inducing 2-1 win over fierce rivals Chelsea at Upton Park.
It leaves West Ham top of the pile as the pride of London with three wins from three derbies and a positive goal difference of plus five.
Arsenal second in both tables
The next best derby performers are Arsenal.
Arsene Wenger's side have played four London derbies this season winning two and losing two. Defeats to the Hammers and Chelsea have been offset by wins over Palace and hated rivals Tottenham Hotspur in the League Cup.
Over the four games Arsenal have negative goal difference of minus two.
Chelsea edge out Spurs into third
Chelsea edge out Spurs to third place by virtue of the fact they have scored more goals, but they have also played one derby more than Mauricio Pchettino's side.
Mourinho's strugglers have played three derbies, winning just once - against Arsenal 2-0 - and losing to Palace and West Ham, both 2-1.
Tottenham are fourth in the London table having only played Palace in the league, a match they won 1-0, although they lost 2-1 to the Gunners in the cup so have an even goal difference.
That leaves Palace at the bottom of the pile despite having played four derbies in the league.
Alan Pardew's side got off to a flier but their weakness is clearly in London derbies which have accounted for three of their five defeats so far this season, to Spurs, Arsenal and West Ham.
There is a long way to go, though, with another 13 derbies to play before the end of the season so it could all change.
The next match between two London clubs comes on Saturday November 7 when Arsenal and Tottenham clash at the Emirates followed by West Ham's visit to Spurs on November 21.
And a fantastic month for London derbies ends on November 28 with Tottenham involved again, this time taking on Chelsea.