Cape Town - Former Proteas captain Graeme Smith is worried that Quinton de Kock's international career is stagnating.

The 37-year-old Smith believes that the batting frailties in the South African ODI setup is the biggest concern as preparations for next year's Cricket World Cup in England.

Speaking to Cricinfo, Smith also had concerns over allrounder Chris Morris, who he believed had not filled his potential on the international stage.

Both De Kock and Morris are in Australia currently where the Proteas are set for three ODIs and a one-off T20I.

The first ODI takes place in Perth on Sunday (05:30, SA time).

"Quinton de Kock - I feel he is stagnating in his career. I would've liked to see him grow into the top echelons like Rohit Sharma and Virat Kohli," Smith said.

"And also Chris Morris. He's a guy who's not quite lived up to his expectations. Whether it's a mental thing or a heart thing, I don't know. But I really want them to step up ahead of the 2019 World Cup."