Former South Africa captain Graeme Smith believes AB de Villiers could retire from Test cricket later this year in order to prolong his international career in the limited-overs formats.
De Villiers, the Proteas captain in ODI cricket, said he would discuss his international future with Cricket South Africa (CSA) in August.
The 33-year-old has not played in the longest format since the beginning of last year, saying he wanted to manage his workload to play at the 2019 World Cup.
Smith says De Villiers, who has scored more than 8000 runs in 106 Tests at an average of 50.46, wanted to quit red-ball cricket in January 2016 but was persuaded to continue to take time out by CSA.
Writing in a column for Britain's Independent newspaper, Smith said: "It's my belief that AB was looking to walk away from the Test game last year at some point, but has been encouraged to carry on by CSA.
"His personal prerogative is ensuring he does all he can to add as much longevity to his international career as possible, as well as taking in to account the harsh realities of touring such as the amount of travel involved, and the toll that takes on your body.
"AB is due to assess his future with CSA later this summer, and my advice to him would be to step away from the captaincy, and concentrate his energy in to maintaining his levels in white-ball cricket for the next two years.
"Put simply, if that is what's best for him and the longevity of his career, then that is what's best for South African cricket.
"Those criticising AB, and this decision in particular, need to ask themselves whether they would rather de Villiers played in the upcoming (Test) series and walked away from international cricket in a year, or have the opportunity to see him go on and play for his country at another big ICC tournament."