Samsung’s Android-based Galaxy S III smartphone model shipped 18 million worldwide during the third quarter of 2012, according to market tracker Strategy Analytics - putting it ahead of Apple's iPhone 4S on 16.2 million.
Neither Samsung nor Apple break out smartphone sales by model.
But we do know Apple said it sold 26.9 million iPhones in total last quarter.
By surveying channel partners, Strategy Analytics has estimated 16.2 million were the iPhone 4S, and 6 million the new iPhone 5, which was released two weeks before the third quarter closed (putting it ahead of Samsung's Galaxy S III if you add the two together).
Samsung has said the Galaxy S III is on track to sell 30 million by the end of this year.
Statetgy Analytics says the strong early iPhone 5 sales indicate Apple will regain the lead in the current quarter.