Durban: Opener Cameron Bancroft struck a fluent half-century as Australia tightened their grip on the first test against South Africa, helping his side to 112 for three at lunch on the third day at Kingsmead on Saturday.

The tourists have extended their second innings lead to a commanding 301 and in-form captain Steve Smith (16) will resume after the interval with Shaun Marsh (four).

The lead already looks a commanding one on a wicket likely to deteriorate in the final two days, providing Australia’s vaunted seam attack with prodigious reverse swing and spinner Nathan Lyon plenty of rough to trouble the batsmen.

South Africa will be disappointed with their bowling effort as they erred in line and length, but left-arm spinner Keshav Maharaj was again the pick of their attack with figures of 2-49, including the wicket of Bancroft (53) on the stroke of lunch.

Australia began their second innings at the start of the third day as Bancroft and David Warner (28) put on 56 for the first wicket before latter miscued a pull off Kagiso Rabada (1-11) to substitute fielder Wiaan Mulder at mid-on.

Usman Khawaja (6) never looked settled at the crease and he was caught by wicketkeeper Quinton de Kock having gloved a ball from Maharaj.

Bancroft continued to play positively and reached his second test half-century off 76 balls with 10 fours, but then walked past a Maharaj delivery and was stumped five balls before the interval.

Australia won the toss and elected to bat in the first of four tests and posted 351 in their opening innings, before skittling South Africa out for 162 in reply on day two.