The key to Marsh's form resurgence

Australia head coach Darren Lehmann believes a new-found belief has been the catalyst behind Mitch Marsh's recent purple patch that has seen him cement his spot in Australia’s middle order.

Marsh played an integral role in Australia's 118-run victory in the first Test at Kingsmead, first with the bat on the opening two days and then with the ball on the fourth afternoon.

The 26-year-old came within a couple of inches of scoring his first Test ton on foreign soil when he was caught by leaping giant Morne Morkel attempting to drive Vernon Philander over mid-on just four runs short of three figures.

Marsh now averages 84.40 since his recall to the Test side during the Magellan Ashes, with four out of the six innings he has played lasting more than three hours having never clocked more than 164 minutes at the crease in the previous 35 knocks.

It's a sign of Marsh’s maturity and new batting temperament, traits that were on display early in his first innings before he unleashed his brutal striking power as he quickly approached a ton.

"He's been fantastic, hasn't he?" Lehmann told reporters in Durban. "He played really well this game.

"He’s worked really hard. We saw a lot in his ability early on to give him a really good run at it.

"He believes he belongs, that’s the biggest thing in Test match cricket to believe you belong at the level and I thought he played beautifully.

"He looks more relaxed, ready to go and play a brand of cricket that's going to change games when you need to."

While Marsh's 173-ball stay in the first innings ultimately helped the tourists conjure a match-winning total, it was also his cameo with the ball - and the wicket of Proteas opener Aiden Markram - that delighted coach Lehmann.

Marsh was surplus to requirements with the ball on day two as Australia’s destructive attack ran through the Proteas in just 51.4 overs to claim a significant first-innings lead.

But as the South African duo of Markram and Quinton de Kock compiled an impressive counter-attack in the home side’s monumental run chase, captain Steve Smith turned to Marsh looking for the breakthrough on a slow Kingsmead surface.

Marsh found some extra bounce to take the edge of Markram's bat and, with a stunning piece of glovework from Tim Paine, break the key partnership and dash any real hopes of a miraculous South African victory.

Lehmann now expects Marsh to again play a key role in the second Test at St. George’s Park in Port Elizabeth, starting on Friday, on a pitch that many expect will play quite similar to the one seen in the series opener over the past five days.

"He got the key wicket yesterday for us, obviously a great catch from Paine,” Lehmann said. "You need that, especially if you’re going to play on wickets that reverse.

"We think Port Elizabeth will be very similar, it was last time (four years ago).

"I think that will be the opposite the last two Test matches.

"You need that extra firepower in a four-Test series when it’s so close together."

Qantas tour of South Africa

South Africa squad: Faf du Plessis (c), Hashim Amla, Temba Bavuma, Quinton de Kock, Theunis de Bruyn, AB de Villiers, Dean Elgar, Heinrich Klaasen, Keshav Maharaj, Aiden Markram, Morne Morkel, Wiaan Mulder, Lungi Ngidi, Vernon Philander, Kagiso Rabada.

Australia squad: Steve Smith (c), David Warner (vc), Cameron Bancroft, Pat Cummins, Peter Handscomb, Josh Hazlewood, Jon Holland, Usman Khawaja, Nathan Lyon, Mitchell Marsh, Shaun Marsh, Tim Paine, Jhye Richardson, Chadd Sayers, Mitchell Starc.

Warm-up match: Australia beat South Africa A by five wickets. Report, highlights

First Test Australia won by 118 runs. Scorecard

Second Test St George's Park, Port Elizabeth, March 9-13. Live coverage

Third Test Newlands, Cape Town, March 22-26. Live coverage

Fourth Test Wanderers, Johannesburg, March 30-April 3. Live coverage