Hampshire 58 for 0 (Gubbins 37*, Albert 21*) trail Glamorgan 536 for 7 dec (Carlson 209, Zain 143, Dickson 54*) by 478 runs Kiran Carlson thumped his maiden Rothesay County Championship double century as Glamorgan oppressed Hampshire at Utilita Bowl.
Carlson had previously topped out on 191 and 192 in first-class cricket but took full advantage of a batting pitch with a highly entertaining innings. His 209 is the highest score in Division One this season.
He put on 318 runs with Zain-ul-Hassan - who ended with a massive career-best of 143 - which was just 10 runs shy of Glamorgan's all-time highest second wicket partnership.
Sean Dickson also fired a half-century as Glamorgan pulled out on 536 for 7, before rain delays paused the Welsh side's momentum.
Cardiff-born Carlson had been imperious from the moment he arrived at the crease just before lunch on day one, with ul Hassan quietly holding the fort from the other end.
Carlson scored over a thousand runs to help Glamorgan back into Division One for the first time in 21 years and has found the top tier just as suitable for his style.
Now captain, having taken over from Kent-bound Sam Northeast, he debuted in Division One with a half-century before a 95 last week proved he was at home. His double century was never dull, plastered with 28 boundaries to all angles, not just the tiny leg side boundary, as he dominated a weary bowling attack.
Hampshire had got day one very wrong, starting with deciding to bowl first on what turned out to be the perfect batting pitch, which was exacerbated by inconsistent bowling.
The main thing that changed for them on day two was luck turned on their side.
Fletcha Middleton broke the mammoth ul Hassan-Carlson partnership with a direct hit with one stump to aim at from deep point, and then Codi Yusuf found a springy part of the wicket to have Ben Kellaway caught behind for a duck - having waited almost six playing minutes with his pads on.
It also meant Hampshire had a bowling point for their long hard day-and-a-half grinding in the field, whereas Glamorgan ended up with four batting points in the 110 overs.
From then on, the hosts had to wait for wickets to land on their lap, as Glamorgan upped the ante ahead of a declaration.
Carlson was finally defeated when he chipped to short cover before Colin Ingram scored quickly then picked out deep square when not fully committing to a flick.
The part-time spin of Tom Prest had Chris Cooke caught behind and Timm van der Gugten swishing straight up just after lunch.
Sean Dickson gave Hampshire one last salvo of chasing leather with a 61-ball fifty, brought up when one fielder kicked the ball into another and conceded a boundary - it summed up 132 overs of pure domination from Glamorgan.
It was almost a mercy for them when Glamorgan declared shortly after on 536 - their highest score against Hampshire - at 14:00 BST.
Hampshire's openers Nick Gubbins and Toby Albert were then given an uncomfortable spell where they were unsure of how long they would have to survive before the forecast rain arrived.
The bowling they faced was also uncomfortable as 'oohs' and 'aahs' followed most deliveries, with Van der Gugten and Jamie McIlroy probing the fourth stump line.
The rain eventually arrived at 14:35 BST, after six and a half overs. There were two brief returns, which also went wicketless as Hampshire confidently reached 58.
