Billy Root hit a career-best 229 as he led Glamorgan into a powerful position against Northants.
Root struck 30 fours and a six to earn the Welsh county a first-innings lead of 243 on day two, after coming in when Glamorgan had slipped to 20/3.
"Very pleasing to get a CB, when I first went in it was tricky and the ball was seaming about so I was just concentrating on getting through little periods in the game," said Root.
"Then the longer that went on I was allowed to score more freely and it was nice to have partnerships with Dan and Tom who played really well, and the scoreboard's always moving when Marchant plays.
"My first 30 runs were through third man, I got dropped out nought so I had a lot of luck and I'm just glad I made use of it. It's pretty pleasing to have got through that tricky period, being able to make a contribution to a very good score and the first time (in 2019) we've got full batting points.
"We're in a great position and hopefully the bowlers will be able to back up a great (first) day for them."