Veteran Murray Goodwin again showed his appetite for runs remains but was upstaged by Chris Cooke, 13 years his junior, as Glamorgan responded cautiously to Hampshire's first-innings total of 349.
At the close of the second day at the Ageas Bowl, after 41-year-old Goodwin laboured more than three hours for his 51, Cooke recorded his first championship half-century and was unbeaten on 73.
Glamorgan ended 123 behind on 226 for four from 67 overs, with Cooke having hit 14 fours in a stay of 103 balls.
Hampshire were 261 for six overnight and added a further 88, with pace bowler John Glover taking two of the four wickets to fall in the morning session.
James Vince, 51 not out, added another 10 runs before Graham Wagg found the edge and captain Mark Wallace took his fifth catch of the innings.
Adam Wheater followed when Glover had him caught by Will Bragg and Glover struck again by breaking through Sohail Tanvir's defences.
Chris Wood hit a robust unbeaten 32, including a six off Dean Cosker, but the experienced spinner ended the innings when last man David Griffiths edged to Marcus North at slip.
Glamorgan did not make the most promising of starts, Tanvir bowling Bragg for 12 before Griffiths removed his opening partner Gareth Rees on 45, knocking back his off stump.
The visitors’ hopes rested on North and Goodwin, their most tested batsmen, and they responded on a wicket easing all the time with a stand of 70.
North was then bowled by a sharp delivery from left-arm paceman Wood after making 36, but Goodwin dug in.
Alongside Cooke, Goodwin added another 55 important runs to blunt the Hampshire attack in the afternoon session.
But after facing 120 balls and hitting seven fours, it was almost a surprise when the obdurate Goodwin, in sight of his 23,000th first-class run, was leg before to spin bowler Danny Briggs with an indeterminate shot.
That did not stop Cooke, whose previous best first-class score was 44; with Jim Allenby for company, he helped add 56 in the evening sunshine. The latter will resume with 15 to his name.