Keaton Jennings has endured a rough start to his first home summer in Test cricket but has not once allowed his head to drop, with his England team-mate Jimmy Anderson tipping the opener’s battling performance on a rain-affected third day to kick-start a return to form.

A century on debut in Mumbai in December augured well for the left-hander’s international career but this season has been a chastening one. A duck on day one meant Jennings went into the second innings with one foray into double figures in five innings but he will resume on Sunday unbeaten on 34 as England look to increase their lead.

Jennings has been catnip to Vernon Philander – the seamer had removed him three times for two runs before Saturday – but finally enjoyed some fortune in this new-ball duel when Dean Elgar shelled an edge at third slip when the batsman was on six.

A smart review on 33, when given out caught behind off Kagiso Rabada, was another heart-in-mouth moment.

Anderson, who had earlier completed figures of three for 25 as the tourists were finally bowled out for 175, has been impressed by Jennings during his lean spell. He believes the way he handled Morne Morkel – the giant quick roared in from the Pavilion End and bowled Alastair Cook with a peach of a delivery – is promising.

“Sometimes you do see it in people that, when they go through a bad trot, they are physically struggling in and around the group,” said England’s record wicket-taker.

“But he’s been really good, he’s dealt with it very well. It’s frustrating but seeing how he got through that tricky period today, that might be what he needs to kickstart a good trot.”

While Jennings will hope to cement his place with a significant contribution, one man who Anderson believes is already looking a solid bet for this winter’s Ashes tour is Toby Roland-Jones. The seamer claimed the final wicket of Temba Bavuma for a gritty 52 to become the first England debutant since Graham Onions in 2009 to claim a five-wicket haul.

The 29-year-old put England on course to regain a series lead with his devastating burst on the second evening and the overcast and floodlit conditions, as well as a green-tinged pitch, suited his nagging line and length,

Anderson said: “I have been very impressed. It’s not often you see a debutant settle so quickly – he looked very comfortable and very confident.

“It helps that he’s had a good career with Middlesex, so knows his action and knows his game. He’s a very intelligent cricketer, very good to talk to about bowling and he thoroughly deserved his five wickets.”

Asked about the chances of seeing Roland-Jones in Australia this winter, Anderson added: “He’s got bounce, swing and seam – so he’s got all the attributes there to do well in Australia. “But he’s only one game in, so let’s take things one step at a time.”

With only 37 overs bowled on Saturday, Anderson revealed England’s plan was to give themselves four sessions in which to bowl out South Africa – provided the weather clears up – on a pitch showing some variable bounce but Bavuma said the tourists have the belief a 1-1 scoreline can be taken to next week’s final Test at Old Trafford.

On Philander, who spent the previous night in hospital on a drip due to a stomach virus but returned, first to bat in the morning from No11 and score 10 not out and then send down six wicketless overs for 30 runs with the ball, Bavuma added: “Vern is a competitor; he’s not someone to give in.

“His efforts over the past three days give testament to that and, as players, we can only respect him more.”