Alex Hales said he was not aware he was closing in on the highest one-day international score by an Englishman in his scintillating 171 against Pakistan on Tuesday.
Hales surpassed Robin Smith's 23-year record as England amassed the highest ever ODI total and claimed a series victory in their 169-run win.
The 27-year-old, who averaged 18 in the preceding four-Test series and had a top score of 14 in the ODIs, said: "The last six weeks have been tough, so to perform like that is pleasing."
The right-hander, playing on his home ground at Trent Bridge, added: "When I got past 150 it came into the back of my mind but I was only aware when the guy announced it.
"It was only when I hit the boundary and the cheering started that the penny finally dropped."
It was a record-breaking game for England, as wicketkeeper Jos Buttler struck the quickest half-century by an England player from just 22 balls.
England hit 59 boundaries - the most conceded in an ODI - after a poor fielding display by Pakistan.
"We missed chances, especially getting wickets with no balls and dropping catches, which didn't help," Pakistan captain Azhar Ali said.
"There were always runs on that pitch and we leaked too many. It was hard to take the control back."
Hales' innings showed how far England's one-day cricket has come since their disappointing 2015 World Cup campaign, when they were eliminated in the group stage.
"That's the most exciting thing for us; that we're still improving," added Notts opener Hales.
"To get the world record is a credit to the work we've put in and what we're hoping to achieve."
What the pundits said
Ex-England spinner Graeme Swann on Test Match Special: "I've got to take my hat off to Alex Hales - he played the world's worst one-day innings by an opener at Lord's three days ago, but he came out and played an incredible knock here. He rode his luck, but by the end his ball-striking was phenomenal."
Ex-England seamer Isa Guha on Test Match Special: "Someone who can absorb that pressure and come out and play the way Hales did belongs on the international stage. And let's not forget the role Joe Root played."
England captain Eoin Morgan: "Alex Hales' innings today was monumental. He has needed runs this summer and today they have all come at once. International cricket is about managing lower times as well as higher times. He fully deserves all the recognition."