England opener Andrew Strauss smashed 164 not out to put Middlesex in control of Northants on day one of their Division Two match at Wantage Road.
Strauss guided his side to 291-1 and is closing in on his first-class best of 177, achieved in England's final test in Napier last winter.
Billy Goodleman was dropped without scoring but went on to make 41 before falling to England's Monty Panesar.
Strauss and Owais Shah (69no) put on 190 when bad light ended play.
Strauss' majestic 164no came from 199 balls with 25 fours and two sixes.
Northants' David Wigley found Goodleman's edge a number of times and bowled beautifully but finished with the unflattering figures of 83-0.
Goodleman fell short of registering his 10th first-class fifty, pushing forward to attempt a paddle sweep being stumped by Niall O'Brien.
Shah, who has amassed 769 runs in his 11 Championship appearances this season, played watchfully early on but breezed to his half-century after the lunch break when he took seven off a Steven Crook over.
And Strauss moved past the 150 mark in the 62nd over when Northants captain Nicky Boje was forced to resort to 22-year-old Riki Wessels to try to break the Shah-Strauss dominance.
Strauss smashed Wessels' third delivery for four and added two more runs before striking another boundary to take him ever closer to his lifetime best.
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