Seamer Timm van der Gugten took 5/45 on his return to the Glamorgan team as the Welsh county bowled Northamptonshire out for 281 on day one.
The Dutchman missed the game at St.Helen's due to international commitments however bowled a terrific spell with the second new ball which saw Northamptonshire lose their last five wickets for just six runs.
"They put a pretty good partnership together between Levi and Wakely (of 118), so it was good to break that and to run through the tail means we don't have to come out and bowl again, hopefully the batters can bat all day and give us bowlers a bit of a rest!" said van der Gugten.
"As a bowler you always felt you were in the game, at the start it seamed around and then it swung all day, so it's one of those wickets you have to dig deep as a batter.
"It was always the plan I was going to play a couple of games for Holland (last week), so it worked out out well as I missed one of the back-to-back games and I felt pretty fresh compared to some of the other guys."