Glamorgan 139 for 5 (Selman 79*) trail Northamptonshire 321 (Kleinveldt 91, Evans 74, Zaib 65) by 182 runs
Northamptonshire ended the second day in Swansea with the advantage after Rory Kleinveldt clubbed 91 before reducing Glamorgan to 139 for 5.
At one stage they lost 3 for 1 in five deliveries and will hope Nick Selman, who closed unbeaten on a career-best 79, can continue the impressive form he's showed in the last three games, and also receive support from the middle and lower order. Azharullah was the most successful of the Northants attack finishing with 3 for 34.
Earlier, Northants had continued their recovery from 38 for 4 to post 321 with their stand-in captain Kleinveldt leading the way with a furious attack on the Glamorgan bowlers.
He scored 91 from 88 balls, with four fours and seven sixes - four struck in the space of six balls. Kleinveldt shared a partnership of 130 in only 24 overs with Saif Zaib - playing in only his second Championship game - before the captain departed attempting to hit his eighth six.
Zaib was undefeated on a career-best 65, which complemented an earlier partnership of 97 between David Murphy and Laurie Evans for the fifth wicket. Murphy made 45, and Evans, in his first innings for Northants since joining as a loan player this week, a patient innings of 74 before edging David Lloyd to the wicketkeeper.
The young and inexperienced Glamorgan attack stuck to their task, despite the seven bowlers used having not taken 100 first-class wickets between them.
Selman and Mark Wallace gave Glamorgan a positive start, adding 52 at four an over, before Wallace was bowled in Azharullah's third over. Will Bragg scored a single from the last ball of the over, but was leg before to the first ball of Ben Sanderson's next over before Jacques Rudolph was caught behind two balls later.
Selman was untroubled at the other end, reaching his third successive fifty from 67 balls with seven fours, but Glamorgan soon lost two more wickets when Aneurin Donald and Lloyd were both caught in the slip cordon, driving at Azharullah's outswing.
Both teams have suffered casualties, with Rory Smith unable to bowl for Glamorgan again in the game, while Northants had two players off the field for the final half hour, with the team's strength and conditioning coach making a rare appearance as a sub fielder.