The world No 6 prevailed 3-6, 6-1, 6-0 against second-ranked Swiatek in an hour and 37 minutes to end a five-match losing streak against the Pole. The head-to-head is now 6-5 in Swiatek's favour.
Rybakina remarkably won the last nine games and 11 of the last 12 games as she stormed to the finish line.
Swiatek destroyed Madison Keys 6-1, 6-2 in her opening round robin match in Riyadh, and she continued her impressive form in the first set against Rybakina.
But things swiftly unravelled for the six-time Grand Slam champion thereafter, though, as she hit 36 unforced errors across the second and third sets.
Rybakina, a Wimbledon champion in 2022, lost just 12 points in the third set as she hit 15 winners to seven unforced errors.
Rybakina has moved top of Group Serena Williams with two wins, having dismantled Amanda Anisimova 6-3, 6-1 in her opening round robin match.
The Kazakh’s place in the semi-finals will be confirmed if Amanda Anisimova beats Madison Keys in the second match on Monday.
Irrespective of that result, Rybakina will progress to the knockout phase as the group winner if she beats Keys in her final round robin match.
Swiatek’s defeat leaves her qualification hopes in the balance heading into the third and final set of round robin matches.
Given Swiatek beat Keys in straight sets and won a set against Rybakina, she is still in with a strong chance of qualifying if she defeats Anisimova in her final match.
It is possible that Swiatek could qualify even if she loses her last match as she, Anisimova and Keys could all finish with one win and two losses.
In the scenario of a three-way tie, qualification would be decided by total sets won and total games won.
