Kabir Ali and James Tomlinson shared six wickets between them as Hampshire bowled out Glamorgan on the last of their four-day match to claim a 31-run victory.
Ali took three for 42 and Tomlinson three for 45 to deny the visitors their first win of the season at the Ageas Bowl.
Glamorgan started the day on 53 for two, needing a further 210 runs to win and, with Australian Marcus North hitting a solid 69 of 102 balls, looked more than capable.
Glamorgan were 212 for six at one point and needed just 50 more runs with four wickets remaining on a sunny day with good batting conditions.
But the last four wickets went down for just 19 runs showing why Glamorgan have struggled so far this season.
Glamorgan got off to a bad start with opener Gareth Rees (21) going early on dismissed leg before by Tomlinson.
Number four North steadied the innings though, hitting 11 fours on the way to a brilliant knock of 69. North and Ben Wright put on a fifth-wicket stand of 60 before the Aussie was clean bowled by David Balcombe after showing true international class.
All-rounder Jim Allenby came in to partner Wright and he tried steady the ship for Glamorgan who were five down.
That was until Wright (32) was caught by the impressive Dawson off the bowling of Balcombe (two for 46).
It looked to be same old story for Glamorgan, showing a distinct lack of fight with another wicket falling without adding to the 168 on the board.
Allenby (23) went off the bowling of Tomlinson, wicket-keeper Matthew Bates taking a good catch to leave Hampshire facing the Glamorgan tail.
John Glover and Mark Wallace put on a stand of 44, pushing without-a-win Glamorgan into a good position going into the afternoon session.
That was until Glover was caught by Simon Katich off the bowling of Dawson, who is having a solid season for Hampshire.
Glover had dug in for his side, scoring 15 runs off 69 balls.
Two runs later, Wallace was walking back to the pavilion, Katich taking another excellent catch off Ali after scoring 29 tough runs.
It looked bad for Glamorgan and soon Wallace was being joined back in the pavilion by Dean Cosker who had not troubled the scorers.
Last in was Michael Reed but he could not see his team home, going for four, James Vince taking the catch from Ali's brilliant bowling.