It’s an even game, agree Curran and De Kock

Curran took four wickets for England, while Quinton de Kock played a crucial innings of 95 for South Africa as the hosts finished the day on 277 for nine after being sent in.

"I think it’s 50-50 at the moment," said De Kock. "The wicket is quite tough to bat on. It was difficult the whole day. If we can get to 300 it will be a challenging score. The wicket will get more difficult to bat on."

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Curran, who took four for 57, added: "It was a pretty even day.

"It was tough going. It was a very warm day with not much breeze. It’s been a tough week for us as a squad and we’re pretty pleased with the way we stuck together as a group today, making sure that we fight for one another and sticking with the guys who are a bit ill."

Three of the England squad – Ollie Pope, Chris Woakes and Jack Leach – were too ill to travel to the ground while all-rounder Ben Stokes was off the field for two extended periods because of dehydration.

It could have been a lot better for England – and worse for South Africa. The hosts were in deep trouble at 111 for five before De Kock counter-attacked to make a half-century off 45 balls.

De Kock played some risky strokes early in his innings but was more circumspect after his initial flurry of strokes.

Having been 64 not out off 69 balls, De Kock needed 59 balls to add 31 more runs before fellow left-hander Curran had him caught behind.

"I wasn’t trying to go at whatever strike I was going at, to be honest," he said.

"I was just trying to get myself into good positions to show some intent, to compete out there."

New cap Dwaine Pretorius made 33 and helped De Kock add 87 for the sixth wicket, while Vernon Philander, who finished on 28 not out, shared in a seventh wicket partnership of 47.

De Kock said he had not needed to help calm any nerves that Pretorius might have felt on debut.

"He was calming me down, he’s a very calm person," he said. "We were just trying to make sure we kept our momentum by keeping the score ticking over."

Curran was the best of the England bowlers, keeping a fuller length than his team-mates, slanting the ball across right-handed batsmen, with some balls swinging back in and others moving away.

"I was pretty pleased," he said of his performance.

"Coming into the series I was really excited. It’s my first time playing Test match cricket in South Africa and it’s an exciting challenge."

Stuart Broad, recovered from illness which prevented him from bowling in his team’s two warm-up matches, took three for 52

James Anderson, playing in his 150th Test – the first specialist bowler to reach the milestone – took a wicket with the first ball of the match when Dean Elgar nudged what looked no more than a leg side loosener to wicketkeeper Jos Buttler. But the veteran had no further success.

Zubayr Hamza, batting at number three in his third Test, played a promising innings of 39, which proved to be South Africa’s second-highest score