England's Ben Stokes said he felt "under pressure" before his record-breaking double century on day two of the second Test against South Africa.
The 24-year-old hit 258 in Cape Town, reaching 200 off 163 balls, the fastest double century by an Englishman and the second fastest ever.
Stokes had made only one fifty in his previous 13 innings.
"I haven't really done much for a while so it was nice to kick on and make a big score," he said.
"I probably won't play like this ever again in my life, but I've done it once so at least I can say that."
After his innings at Newlands, Stokes added: "I normally say 'crikey' when I get to 30, to be honest, so I kept on looking at the scoreboard."
'Trying to hit every ball for six'
Stokes, whose 11 sixes was the most by an England batsman in a Test innings, hit 130 runs in the morning session as the tourists flayed South Africa before eventually declaring on 629-6.
When he was finally dismissed, Stokes had made the highest ever score by a Test number six, beating the 250 of Doug Walters for Australia against New Zealand in 1977.
Stokes was eventually run out after sharing a Test record sixth-wicket stand of 399 with Jonny Bairstow, who made his maiden Test century.
When England reached 600, Stokes said captain Alastair Cook asked him if he wanted to delay the declaration so he could chase a triple century.
"I said it doesn't really matter because I'm just trying to hit every ball for six anyway," revealed Stokes.
Stokes in numbers - the records he broke
- Fastest Test double century by an England batsman
- Highest score by an England batsman at Newlands, beating Jack Hobbs' 187 in 1910
- Most sixes by an England batsman (11), surpassing Wally Hammond in 1933
- Most runs scored in a day of Test cricket at Newlands, beating the 450 made by Australia at Wanderers in 1921
- Highest score by a number six, bettering the 250 of Doug Walters for Australia against New Zealand in 1977
- Stokes and Bairstow set the highest partnership for a sixth wicket in Test cricket
- Stokes and Bairstow set the fastest 300 partnership, beating India's Virender Sehwag and Rahul Dravid
'The best day of my life'
Bairstow, the England wicketkeeper, made an unbeaten 150 to register a maiden century in his 22nd Test.
"It's probably the best day of my life," he said. "It's been a little while coming and I'm delighted to get over the line.
"It's fantastic, not only for myself, but my family as well."
Bairstow is the son of former England wicketkeeper David, who took his own life in 1998 at the age of 46.
"I was thinking of my dad and my grandpa, who passed away last year," said the 26-year-old.
"My mum was up there in one of the boxes, my sister as well. It's a special day for all the family... both here and up there."
'We're massive favourites'
South Africa moved to 141-2 at the close at Newlands, with captain Hashim Amla 64 not out and AB de Villiers, who was dropped by Joe Root, unbeaten on 25.
"We're massive favourites at the moment, we're so many runs ahead," said Stokes.
"De Villiers and Amla are the two big wickets, so we'll be looking to get them early tomorrow.
"It will be a big ask on a nice wicket, but we know that, once we get them, they can have a fragile tail with not many runs under their belts."
Spare a thought for South Africa
"It was a very intense show from Stokes and a crazy day of cricket," said Proteas opening batsman Dean Elgar.
"We tried various game plans against them, but it was one of those days where nothing went right.
"All you can do is take your cap off at the end of the battle.
"We were a little shell-shocked the way things were going."