Veteran Northamptonshire seamer Ben Sanderson took three wickets to lead a Northamptonshire attack that made the most of the return of the Dukes' ball on the opening day of the Vitality County Championship match at Wantage Road.
But despite being 27 for 4 after 10.4 overs, Colin Ingram led Glamorgan's fightback with an unbeaten 69 off 110 balls. He steered the visitors to 203 for 7 at the close of play, with the scores on the first evening almost even.
Solid in defence, Ingram played some crisp shots in the attack as he rebuilt, first in a partnership of 69 in 18.3 overs with Chris Cooke (28). Despite losing Cooke after tea, the in-form Ingram continued to press on, scoring his second successive half-century of the season to add to his opening century. He found another willing partner in Dan Douthwaite, whose blistering 50 came off just 63 balls in a 102-ball 74 for the sixth wicket.
Earlier, Northamptonshire won the toss and elected to bowl after heavy overnight rain washed out the morning session. The atmosphere encouraged movement through the air and off the seam as Northamptonshire's bowlers stuck to a controlled, probing line around off stump.
Sanderson, in particular, proved unplayable at times. He was well supported by Australia's Chris Tremain, while England Under-19 international Raphy Weatherall also bowled impressively to take two wickets. It was a stark contrast to last weekend's run-fest against the Kookaburra ball.
It was Tremain who struck first, getting a fuller delivery to swing in and then seam away to take the edge of Zain-ul-Hassan's bat, with keeper Lewis McManus taking the catch.
Sanderson challenged Billy Root outside off stump, the batsman playing and missing repeatedly before the bowler got one back to trap him leg before wicket.
Glamorgan skipper Sam Northeast (13) drove Sanderson down the ground for four but survived a close lbw decision against Sanderson as Tremain struck his bat. His brief innings ended when he needlessly flashed at a Sanderson delivery that lifted slightly, Ricardo Vasconcelos holding the edge at third slip.
Kiran Carlson drove a fluent drive through extra cover off Tremain for four, but when he got stuck in his crease facing a Weatherall delivery, he was bowled by a ball that hit his off stump back.
Cooke lived a charmed life early on against Weatherall, the bowler angling one back in and drawing an edge that fell just short of the slip cordon.
Ingram, meanwhile, got off to a good start, pulling Tremain behind square for four, but took on Weatherall as he went round the wicket, hitting him off the back foot for four and then pulling his next delivery high over square leg and out as Glamorgan reached 50 for four after 17 overs.
Cooke drove Luke Procter off the back foot for four, but the Northamptonshire skipper kept a tight line to keep the pressure on the batting side as he rotated his attack.
Cooke hit Sanderson for four to bring up the 50th-wicket partnership, but the bowler had a strong lbw appeal turned down just before the rain returned and the players took an early tea.
On resumption, Sanderson finally got his man with his first delivery of the evening session when Cooke drove loosely off his body and was well caught by Emilio Gay at second slip.
Ingram took a floated full delivery from Tremain and drove it to the cover boundary, taking Procter off his hips to bring up his 78-ball half-century.
Douthwaite saw off Sanderson's post-tea spell, playing him through the covers for four, and took the attacking option. He edged Procter through midwicket and drove Weatherall down the ground, hitting seven boundaries in all before being trapped leg before for Weatherall's second wicket. Procter then trapped James Harris, also lbw, without scoring to leave Glamorgan on 171 for 7.
Mason Crane, however, kept Ingram company until the end, scoring 17 to ensure the visitors had no further scare.
Before play began, the players and officials observed a minute's silence in memory of former Northamptonshire captain Raman Subba Row CBE, who died on Wednesday at the age of 92.