Alastair Cook admitted his relief at ending a seven-month wait for a Test century today - and backed England to capitalise in the second Test at Kingsmead.
The Essex opener crafted a patient 118 before falling to South Africa paceman Morne Morkel shortly after tea.
His innings helped England close the third day 43 runs ahead on 386 for five, and he expressed hope his team-mates can make the most of their strong position.
He told Sky Sports 3: "You only need to look at what happened in the last session in the first Test and how quickly it can change.
"We're in a good position, obviously we have to crack on tomorrow and set the tone again and get the lead as big as we can, but we can't look too far ahead, because a couple of quick wickets and we can let our situation slip a bit. We've got to pile on the runs tomorrow."
On his personal vigil - which occupied 263 balls and 401 minutes - he said: "It's always nice to score some runs.
"I had to be patient - I think in the first hour I scored one run, and probably played about four shots hitting the bat.
"It's an area I've been working on, I haven't left the ball as well as I'd like to have done, so today I was trying to play it when the ball came to me and I thought I did that quite well."
The ton was Cook's third in Tests this year and his 10th in total, but his first since May's 160 in the second Test against the West Indies at Durham.
"It was a relief," he added. "It's been (over) six months without getting another one so there was a bit of pressure leading into this game. It's just nice to contribute to the side today.
"In the last four Tests, since Lord's (against Australia), I've got a couple of 30s and that's about it. As a batter you're there to score runs and if you're not doing that then you feel (pressure) yourself.
"The selectors have never said anything to me, they've stuck by me and hopefully I've repaid a bit of faith today."