The fall of two late Middlesex wickets saw Northants take the advantage at the end of day two of the County Championship match at Uxbridge.
In perfect summer conditions at Park Road Northants made 377 in reply to Middlesex's first innings score of 340.
Rob White hit a superb 127 off 103 balls to entertain the crowd but Northants then collapsed after tea with seven wickets falling as they went from 281-3 to 377 all out, with Tim Murtagh picking up 3-79.
However, in a dramatic end to the second day Middlesex then lost Andrew Strauss and Steve Finn to the bolwing of Johannes Van der Wath and finished on 4-2 in their second innings.
