Northamptonshire look set to claim their second LV= County Championship Division Two win of the season despite half-centuries from Alex Gidman, Benny Howell and Chris Dent for Gloucestershire at Bristol.
The hosts, trailing by 212 on first innings, were largely indebted to Gidman (87), Howell (53) and Dent (50) for guiding them to 280-9 at stumps and an overall lead of 68.
But the Northamptonshire attack stuck well to their task on an easy-paced pitch and there were three wickets each for Andrew Hall and Steven Crook as the early-season pacesetters close in on victory.
Gloucestershire started the day on 34-1 and, with no addition to the total, Dan Housego fell to the fifth ball of the morning when he was caught down the legside by wicketkeeper David Murphy off Copeland.
Gidman and Dent applied themselves well to add 56 in 21 overs, but Dent then attempted to withdraw his bat to a delivery from David Willey and only succeeded in getting an edge on to his stumps.
Marshall departed five overs later, caught at first slip by Copeland off Andrew Hall, and Gloucestershire went into lunch in considerable trouble on 111-4.
The afternoon session started well for the hosts as Gidman and Howell put on 69 for the fifth wicket with few alarms.
Gidman brought up his 95-ball half-century by cutting Copeland to the cover boundary and the county’s former skipper then took three fours in quick succession off Hall.
He also hit off-spinner James Middlebrook for a straight six and appeared on course for a century until he pushed forward to Hall and edged low to Copeland at first slip.
Will Gidman, Alex’s younger brother, was dismissed six overs later when he was caught behind off Crook and Gloucestershire took tea on 188-6, still 24 short of making Northamptonshire bat again.
The visitors only had to wait one over after tea to take the second new ball, but Howell and Cameron Herring sucessfully saw the shine off it with some attractive stroke-play in a partnership of 54.
Teenage wicketkeeper Herring was dropped on nine by Rob Newton at backward point off Crook, but otherwise played impressively in only his second first-class innings.
Howell progressed to a patient 142-ball half-century, with five fours, before he edged Hall to David Sales at second slip to give the South African his third wicket.
Jack Taylor took successive boundaries off Hall, to midwicket and backward point, on his way to an unbeaten 30 at stumps, but there were still two more wickets for Northamptonshire to celebrate in the closing overs.
Herring chipped Crook to Alex Wakeley at midwicket to depart for 32 and the seamer then bowled David Payne for a duck.