Northamptonshire 13 for 0 trail Gloucestershire 358 (Marshall 145, Willey 3-64) by 345 runs
Hamish Marshall struck his fourth century of the season on an even first day at Northamptonshire. Marshall hammered a brilliant 145 off 197 balls including 19 fours and two sixes to help Gloucestershire recover from a shaky start.
A late collapse meant the visitors were bowled out for 358 towards the end of the day with David Willey, Andrew Hall and Muhammad Azharullah each taking three wickets for Northants, who then closed on 13 for 0.
Gloucestershire won the toss and chose to bat but they lost Chris Dent for a four-ball duck in the third over when he edged Willey to Northants wicketkeeper David Murphy. In Willey's next over, Gloucestershire's wicketkeeper Gareth Roderick was trapped lbw for just 2 to leave the visitors 9 for 2.
But Alex Gidman helped his side recover from their poor start by racing to 50 off just 54 ball as part of a partnership of 92 with captain Michael Klinger. But Gidman was to throw his wicket away on 59 when he slashed Hall to Willey at point as Gloucestershire reached lunch on 117 for 3.
Klinger, though, was to fall three runs short of a composed half-century when he was taken by Murphy off the bowling of Hall in the third over of the afternoon.
Marshall then went past 50 off 81 deliveries with a four over extra cover off James Middlebrook as the visitors dominated the rest of the session. He went on to complete his 24th century in first-class cricket - and his third in five innings - off 125 balls before Benny Howell completed his half-century off 84 deliveries in the last over before tea.
But Howell fell on 60 early in the evening when he swept Hall to David Sales at deep square leg to break a fifth-wicket stand of 183. Marshall finally departed two overs after Northants took the second new ball by nudging Azharullah's leg side strangler to Murphy.
James Fuller followed him back to the pavilion as he was bowled by Willey before Will Gidman chopped Azharullah on to his stumps to walk for 15. Craig Miles and Tom Smith were then pinned lbw by Azharullah and Steven Crook respectively, meaning Gloucestershire's final five wickets had fallen for just 20 runs.
Northants captain Stephen Peters and Kyle Coetzer then survived two overs before stumps and will resume tomorrow on 12 and 1 respectively.