Sam Curran believes England let Quinton de Kock get into his stride too easily, but says it was a positive day for the tourists at Centurion.
Curran was the outstanding performer for England as his four wickets helped keep South Africa in check on day one of the first Test.
His haul included the dismissal of De Kock, whose 95 was instrumental in guiding the Proteas – who lost Dean Elgar to James Anderson on the first ball of the day and had been 97-4 – to 277-9 by stumps.
De Kock was fortunate early in his innings as he hit a quickfire 50, but picked his shots with more caution after surpassing a half-century, before eventually edging a Curran delivery through to Jos Buttler.
Though Curran conceded England could have done better to restrict De Kock, he feels he and his team-mates are in a strong position heading into day two.
"Obviously we'd have liked to have bowled them out by the end of the day but to have them nine down and under 300, it's pretty even," Curran told Sky Sports.
"Anytime you choose to bowl first there's going to be a lot of pressure on the bowlers to take a load of the wickets but what a better way to start, with Jimmy [James Anderson] on his 150th Test. A great start and we all enjoyed that.
"De Kock probably got away from us a bit too quickly as the day went on but to get him so he can't bat with the tail was pretty good.
"I think you watch him in one-day cricket and he just plays his shots, he's a great player, so we expected him to play his natural game, even in Tests.
"He probably got away a bit too quickly when he came in, got a foothold. He probably rode his luck a bit as well but fair play to him, he got a good score."
England elected to play five seamers, though all-rounder Ben Stokes was unable to bowl as he struggled with illness and dehydration in the heat.
"I think Stoksey's suffering with dehydration, I started suffering with cramp towards the end, nothing serious, but I managed to carry on," Curran said.
"There was not much breeze and it was pretty hot, so it was tough work but I think we coped well."