South Africa posted 140-6 on Monday in an action-packed first day of the opening Test, after Bangladesh collapsed to 106 all out with Kagiso Rabada celebrating being the fastest to take 300 Test wickets.

The visitors took the lead, reaching 140-6 in 41 overs in reply at stumps at Mirpur, with Wiaan Mulder and Kyle Verreynne not out for 17 and 18 respectively.

Bangladesh won the toss and opted to bat but four of their top six batsmen failed to reach double figures, with opener Mahmudul Hasan Joy top-scoring with 30 on a lively pitch.

Seamers Rabada, Mulder and left-arm spinner Keshav Maharaj took three wickets apiece for South Africa.

Bangladesh were teetering at 40-4 when Rabada bowled Mushfiqur Rahim on 11, as the South African celebrated reaching the 300-wicket landmark.

He managed the feat in 11,817 balls, the fastest of all time, beating Pakistan's Waqar Younis (12,602 balls).

Rabada soon made it 301 Test wickets, removing Litton Das for one, with Bangladesh crumbling, all out for 106 in 40.1 overs.

Rabada said he was "really surprised at how the wicket played out".

"Test cricket should offer a fair contest between bat and ball, where bowlers get something if they bowl well, and batters can score if they apply themselves," he said.

"With 16 wickets on day one, I'd say it's leaning towards the bowlers," he added.