Joe Root is unlikely hero with the ball as England close on big victory in third Test against South Africa

Captain takes four wickets to leave sorry Proteas heading for final day defeat after being forced to follow-on in Port Elizabeth

England fielder Ollie Pope dives to catch out South Africa batsman Rassie van der Dussen during Day 4 of the third Test in Port Elizabeth on Sunday. AP

Ollie Pope catches out Rassie van der Dussen off the bowling of Joe Root. Getty

Joe Root celebrates after taking the wicket of Rassie van der Dussen. Getty

South Africa captain Faf du Plessis goes on the attack. Getty

Quinton de Kock after losing his wicket. Getty

Mark Wood of England takes a catch to dismiss Quinton de Kock. Getty

England bowler Sam Curran. Getty

South Africa batsman Dean Elgar is bowled by England's Mark Wood. AP

England's Sam Curran. AP

Faf du Plessis of South Africa. AP

Stuart Broad of England celebrates after bowling Keshav Maharaj. Getty

England captain Joe Root leads his team onto the field at the start of Day 4. Getty

England spinner Dom Bess celebrates his five-wicket haul at the end of South Africa's first innings. Getty

South Africa's Dean Elgar. AFP

Sam Curran of England celebrates after bowling Quinton de Kock. Getty

South Africa's Keshav Maharaj is bowled by Stuart Broad. AFP

Mark Wood of England keeps himself entertained before the start of Day 4. Getty

England are closing in an innings victory in the third Test against South Africa as their pacemen sent stumps flying and Joe Root played an unlikely starring role with the ball.

The tourists began Day 4 in Port Elizabeth with a blitz of four wickets for just one run as they skittled the Proteas for 209.

Root then took his best figures in Tesdt cricket – 4-31 – as South Africa slumped to 102-6 after being forced to follow on.

With a lead of 188, only further rain can realistically prevent England taking a 2-1 series lead to Johannesburg, with a three-hour delay preventing them from wrapping things up well ahead of time.

They needed only 28 balls to dismiss South Africa's last four batsmen at the start of play, with Stuart Broad picking up three of the wickets without conceding a run.

Bowler Mark Wood called it a "good day" for the tourists. "We put in some tough work, and Broady and Sam started brilliantly," he said. "Our attitude has been good today, and we got our rewards."

Rain early in South Africa's second innings threatened to thwart England's push for victory. But the tourists made the best of every moment they had either side of that downpour, with seamers Broad, Sam Curran and Wood all toppling the timbers to hammer home the scoreboard pressure created by their first-innings 499.

Then it was over to Root, who in 90 previous Tests had never taken more than two wickets in an innings.

Bowling from the end where fellow off-spinner Dom Bess took five wickets in the first innings, he trapped Pieter Malan leg before wicket in the last over before tea.

Root took three more wickets after the interval. Rassie van der Dussen was superbly caught at short leg by Ollie Pope and first innings top-scorer Quinton de Kock fell to a leaping catch at backward point by a leaping Wood.

South Africa captain Faf du Plessis was sixth out after making 36, his highest score of what has been a poor series for him. He was another bat-pad victim, giving Pope his fifth catch of the match.

The pressure is now growing on Du Plessis whose position must be under threat. When asked about his captain's future, South Africa coach Mark Boucher said: "That's not a call to make a this moment in time. He's trying really hard; he's working really hard away from the game. If he's not scoring runs there's that extra pressure. The best way to answer that is putting runs on the board.

"There's no hiding place in Test cricket. He's disappointed from a team perspective. He spent a bit of time in the middle, which is good for his confidence.

"[Overall] I'm disappointed. We didn't have a good day today at all. No excuses. We've got to man up and learn lessons. We were outskilled."