The first of three one-day internationals between Bangladesh and Ireland in Chelmsford, England was washed out Tuesday.
Chasing the Tigers' 246/9, the Irish were batting on 65/3 in 16.3 overs when rain came pouring down, pausing the World Cup Super League fixture in the UK.
Middle-order batters Harry Tector and Lorcan Tucker were unbeaten on 21 and two respectively when rain intervened proceedings.
Spinner Taijul Islam and pacers Hasan Mahmud and Shoriful Islam all bagged one wicket apiece as Bangladesh bowlers came out firing to defend their total.
Persistent rainfall though forced the game to be washed out, thus giving South Africa the eighth and final automatic World Cup spot.
Only a 3-0 sweep would have seen the Irish leapfrog the South Africans in eighth in the World Cup Super League standings and secure automatic qualification for the mega 50-over event in India later this year.
The first spots in the 10-team World Cup go to the top eight finishers, a competition that has run over the last three years.
Reigning champions England, India, New Zealand, Australia, Bangladesh, Pakistan and Afghanistan have already assured their places.
And now the washout means the Proteas became the last team to seal automatic qualification.
The bottom five Super League teams travel to the World Cup qualifier in Zimbabwe from June 18 that will decide the final two entrants into the main event.
Earlier, the Tigers posted a competitive 246 after being asked to bat first, riding on useful contributions from Mushfiqur Rahim (61) and Nazmul Hossain Shanto (44).
Wicketkeeper-batter Mushfiq struck half a dozen fours in his 70-ball knock while No 3 batsman Shanto hit seven boundaries in his 66-ball stay at the crease.
Seamer Josh Little led the way for the Irish with 3/61.