The Boks could have used a player of Pienaar's experience and versatility on tour to Europe, and at the Rugby World Cup in Japan next year, but he says that chapter of his career is now firmly closed.
Deysel, who joined Ulster from Guinness Pro14 rivals Munster in 2017, made his decision because of a "combination of lower-body injuries and various niggles".
Former Wallaby Henry Speight scored a try in a dramatic finish to ensure a draw for Ulster in their PRO14 encounter against the Cheetahs in Bloemfontein on Friday.
Former Springbok loose-forward Marcell Coetzee rock the shackles with a second-half try to help Irish side Ulster to a 28-7 victory over hosts the Southern Kings in their PRO14
Ulster have reached an agreement with Scottish Rugby for Dan McFarland to begin as their head coach from Monday after he was released from his contract.
Ulster could be without star winger Jacob Stockdale until October after a hamstring injury ruled him out before the start of the new season.
Australia international Henry Speight has joined PRO14 side Ulster on a six-month contract.
Ireland, Ulster and British & Irish Lions centre Jared Payne has been forced to retire after being unable to recover from a head injury sustained on the Lions' tour of New Zealand last year and will take up a coaching role with the Irish province.
Joe Schmidt has named uncapped duo Ross Byrne and Tadhg Beirne in Ireland's squad for their summer tour of Australia next month.
Ireland and Ulster wing Andrew Trimble has announced he will retire at the end of the season.
Sale have announced that they will not be signing Paddy Jackson and Stuart Olding.
Ulster have named Scotland assistant Dan McFarland as their new head coach.
Ulster Rugby have confirmed current Scotland assistant coach Dan McFarland as their new head coach for next season after he signed a three-year deal with the Irish Province.
Charles Piutau tells ESPN why he is refusing to give up on his dream of playing at a Rugby World Cup, and what the game needs to do to help the Pacific nations.
Ulster's former All Black Charles Piutau is determined to "make the jersey proud" as he aims to help deliver Champions Cup qualification in his final two appearances for the Irish province.
The Irish Rugby Football Union and Ulster Rugby have revoked the contracts of Paddy Jackson and Stuart Olding with immediate effect.
Ulster Rugby sponsor Bank of Ireland (BOI) has told the province that it is "highly concerned" with the behavioural and conduct issues that arose during the recent rape trial which saw player's Paddy Jackson and Stuart Olding acquitted March 29.
Ulster fly-half Paddy Jackson admitted he was ashamed as he apologised for his behaviour that led to him facing rape charges, which he was cleared of last week.
Ulster player Craig Gilroy has apologised "unreservedly" for a WhatsApp message he sent which was used in the rape trial of teammates Paddy Jackson and Stuart Olding.
Ireland internationals Paddy Jackson and Stuart Olding have been cleared of rape following an eight-week trial in a Belfast court.
Ireland captain Rory Best and fullback Rob Kearney have signed new contracts with the Irish Rugby Football Union until the 2019 World Cup.
Jono Gibbes will leave his post as Ulster head coach at the end of the PRO14 season to return to his native New Zealand.
Ireland and British & Irish Lions wing Tommy Bowe has revealed he will bow out of professional rugby at the end of the campaign.
Ulster director of rugby Les Kiss was a happy man after his side's six-try 52-24 bonus-point victory over Harlequins which secured second spot in Pool 1 of the European Champions Cup.
The Champions Cup is set for another enthralling weekend of action as the return legs of the double headers are played and pools continue to take shape.
- ULST7thTRIES SCORED 1st Leinster : 27 Tries ScoredLEINS1st1827
- ULST10thPOINTS DIFFERENCE 1st Leinster : 116 Points DifferenceLEINS1st3116