Mark Wood joked England captain Joe Root had pulled rank on the way to achieving his Test-best bowling figures on day four of the third Test against South Africa at St George's Park.

The tourists' skipper poached 4-31 after Wood struck twice as South Africa's sorry batsmen, following on after a first-innings morning collapse, slumped to 102-6 at stumps on Sunday - trailing by 188 runs.

Root's off-spin caused chaos, taking his lead from Dom Bess, who grabbed five wickets in the Proteas' first knock but had a supporting role second time around.

Wood, playing his first competitive match since England's Cricket World Cup final triumph over New Zealand last July, quipped that Root used his authority to take centre stage in Port Elizabeth.

"He bowled himself at the right end, didn't he!" the paceman said. "Put young Bessy on at the non-spinning end and he got the spinning end. So captain's not stupid is he!

"I feel like he does get key wickets when he bowls. He's been working on it a lot in the nets. As a group we're really pleased for him. Hopefully he gets the 'five-for' tomorrow."

Root had only taken four wickets in a match once before, a 4-5 haul in a winning cause for Yorkshire against Roses rivals Lancashire in 2018.

Wood, however, is no stranger to big performances with the ball, but spending another long spell out of action has been frustrating for the 30-year-old Durham paceman.

"I've waited quite a while to come back in," he said, after taking 2-23. "I'm trying to have fun, trying to play with a smile on my face and take it all in.

"Before the game I wasn't sure how it was going to go. I hadn't played any practice matches, I didn't have any of that match fitness. I was probably a little bit tired at the end of today but all in all I think I've stood up well physically."

Wood suffered his side injury with three balls remaining of his 10-over allocation in the World Cup final, which he called a "dream game".

"I didn't want to limp off after 9.3 overs," he said, stressing bowling on had been a risk worth taking. "I wouldn't swap that for the world. To be a World Cup winner, I'd take that any day of the week.

"Even if I didn't play another game of Test cricket, I've always got that to look back on with great memories and think that was the pinnacle of my career."