By SABC Sport
5th January 2024
The lock is being eased back after being named in Saitama Wild Knights' reserve side for a training match against Toyota Verblitz on Saturday.
De Jager has not played since midway through 2023 after he was diagnosed with a heart condition a day before their Rugby World Cup squad was announced.
His last game came for South Africa against the All Blacks in July 2023, where he played just 43 minutes in a 35-20 defeat at Mt Smart Stadium in Auckland.
The experienced forward was later diagnosed with pericarditis, which is the inflammation of the lining around the heart and can develop from exercising when sick with the cold or flu.
De Jager revealed in December that he was back training after being given the green light from the heart specialist to resume playing.
However, the 31-year-old admitted that it would take a while for him to build up his strength and fitness to be able to play a match.
"I can play again," he told Rapport last month.
"I will have to build up my fitness again after not being allowed to do anything for more than three months. I'm pretty unfit."
De Jager was pencilled in to be back out on the field before the end of January and, just a month after being allowed to restart his career, he will play for the Wild Knights against Toyota in a reserve game.
Due to the heart condition, the lock was forced to watch the World Cup from home as the Springboks claimed their second successive title - and fourth in total.
He was a key part of the 2019 squad that claimed the Webb Ellis Cup, starting five of their matches, including the three knockout clashes.
De Jager only lasted 21 minutes in the final, however, after suffering a shoulder injury that would keep him out of action for four months.
South Africa went on to claim a historic 32-12 victory over England in the showpiece event before they defended their title in France last year.
The second-row has earned over 60 caps for the national team and will now look to put himself back in the international reckoning after recovering from the heart condition.