The Glamorgan batter was given a life on 96 and quickly after going to his first double ton he added a third as Leicestershire were left to rue missed opportunities
Sam Northeast says hitting a maiden triple century for Glamorgan against Leicestershire in the LV= Insurance County Championship "was never in my wildest imagination" after he cashed in at Grace Road.
The 32-year-old avoided being dismissed on 96 after Colin Ackermann missed a slip catch opportunity off Callum Parkinson,and never looked back.
That edge helped him to a 27th first-class century and he doubled up for the first time via his 22nd boundary of the innings.
Another 74 balls later he was celebrating a clinical triple hundred, the first of an illustrious domestic batting career that has never been rewarded with England recognition.
Northeast reached the close 308 not out, a run short of Steve James' 309 against Sussex in 2000 which stands as the highest individual score by a Glamorgan player.
He and Colin Ingram (129) put on 306 for the third wicket, the best for Glamorgan against Leicestershire, before a 229-run stand between Northeast and Chris Cooke (71 not out) took the visitors past the follow-on target of 435.
"There were times when they bowled really well and you had to ride that," he said, according to the ECB Reporters Network. "I gave a chance on 96 but managed to survive that and battled for a bit.

Colin Ingram also road his luck on his way to three figures (Dan Mullan/Getty Images)
"After that, I began to feel it was a situation where I could get to 200 but 300 was never in my wildest imagination and a dream come true in a lot of ways.
"We were in a situation in the game where we needed to take time out of the game, to keep batting and get past the follow-on target, so that was my main priority but, yes, the double hundred was a thing that needed ticking off in my career.
"I've made some big hundreds before without getting a double so there was a bit of relief to get over the line. Then, once we had avoided the follow-on we were able to express ourselves and have a bit of fun at the end and the runs kept flowing."
After watching the south Wales club waste opportunities in the field on day two, it was Leicestershire's turn to rue their average catching as Parkinson and Wiaan Mulder both saw chances come and go alongside a series of near-misses.
Glamorgan will resume on day four on 563 for 5, 21 runs adrift of Leicestershire's first innings 584 - as the Division Two clash saunters towards an inevitable draw.
Northeast left Hampshire last summer and had spells with Yorkshire and Nottinghamshire before signing with Glamorgan for three years.
He added: "It was a strange year in 2021 after deciding to leave Hampshire and then playing on loan for two different counties but I feel I've found a real home at Glamorgan and I couldn't be happier."