Bottom side Eastcote beat Ealing by one wicket to put a dent in the latter's 2013 Middlesex ECB Premier League title chances, allowing Hampstead to go 18 points clear at the top.
Eastcote are virtually certain to be relegated after being deducted 20 points for two separate regulation breaches and are 50 points adrift but stunned Ealing by chasing down 174 with one ball to spare.
That allowed Hampstead, who comfortably beat Finchley by seven wickets, to move to 89 points with Ealing on 71.
Elsewhere, there were wins for Hornsey and Twickenham.
In Division Two, North Middlesex (82 points) thumped Ickenham by 202 runs to extend their advantage over Brondesbury (64), who drew with Brentham.
In Division Three, leaders Kenton (75 points) beat Barnes by five wickets as second-placed side Enfield (68) were held by Highgate.
© Cricket World 2013