Aiden Markram, the South Africa opener, has signed for Durham for the first four games of the County Championship, with the New Zealand batsman Tom Latham taking on the 50-over captaincy when he arrives to fill the overseas spot until August.
Markram, 23, captained South Africa to victory in the Under-19 World Cup in 2014, and was drafted into South Africa's Test squad during last summer's tour of England. He went on to make his debut against Bangladesh in September, scoring 97 in his first innings.
He then added back-to-back centuries in his second and third Tests, against Bangladesh and Zimbabwe, and a further score of 94 during the series win over India. After six Tests, he averages 52.00, and recently captained South Africa's ODI side in the absence of Faf du Plessis.
Markram will arrive at Chester-le-Street in time for Durham's opening home Championship fixture against Kent in April, and will stay until the start of the Royal London One Day Cup in the middle of May.
Latham, who made a strong impression in his maiden season at Chester-le-Street, produced an unbeaten matchwinning century in an ODI against India in Mumbai in October, and earlier this week was instrumental in New Zealand's series-opening victory over England at Hamilton, with 79 from 84 balls. He is expected to play all three formats for Durham.
"We're delighted to have both Aiden and Tom at Emirates Riverside this season," said Ian Botham, Durham's chairman, "and I am confident they will both contribute to what we hope will be a successful season.
"Aiden offers confidence and maturity at the top of the batting order and despite being just 23 years old, he has already been recognised by South Africa as a leader in the dressing room.
"It's great news that we will have Aiden at the beginning of our Championship campaign, especially with Tom Latham, Ben Stokes and Mark Wood all missing due to their international and IPL commitments.
"We're delighted to welcome Tom back to Chester-le-Street and I'm excited to see him captain the RL50; he has a wealth of international experience and brings exceptional batting, fielding and leadership skills into the dressing room."
Durham hope to make further signings for this season's T20 Blast campaign.