Since they met in the Top 14 last four in 2019, the sides have faced each other in two domestic finals and a Champions Cup decider.
Toulouse won all three and ended this Top 14 season at the summit of the league table.
La Rochelle claimed a statement-making win at Toulon in last weekend's play-offs having lost just once in their last six games of the campaign.
Earlier this month Toulouse and La Rochelle played out a thrilling 31-31 draw in their most recent meeting, a week after the former lifted a record sixth Champions Cup.
"We're starting to get to know each other well," Toulouse back-rower Francois Cros told AFP.
"Every time you have to lift the cursor in terms of intensity and strategy to get around them, who have been like a cannon ball towards the end of the season.
"They're getting stronger, winning the play-off at Stade Mayol is not nothing," the France flanker added.
Last season's final win lives long in the memory because of Romain Ntamack's superb last-gasp match-winning try.
Ntamack's 60m solo effort denied La Rochelle a maiden Bouclier de Brennus title as well as a continental and domestic double having lifted a second Champions Cup weeks earlier.
"Toulouse are the in-form team in the Top 14, their progress in the Champions Cup has given them confidence," La Rochelle captain Gregory Alldritt said.
"The revenge is more towards ourselves because it's us who failed to win.
"To be champions we have to get through Toulouse," he added.
'Unplayable'
Partnering Ntamack at half-back this weekend at the sold-out 42,000-capacity Matmut Atlantique will be superstar Antoine Dupont.
Scrum-half Dupont will be looking to finish the club campaign on a high by reaching next weekend's final being played in Marseille rather than Stade de France as it is being prepared for the Paris Olympics.
The 27-year-old will then turn his eye to clinching a gold medal in sevens rugby at this summer's Games having improved even further during his first campaign with France's set-up in the shorter form of the sport.
"The minimum for us to keep the standards from Toulon against the best player in the world in their team," La Rochelle's director of rugby O’Gara said.
"In certain games he's unplayable.
"We've never seen a player like him, especially in recent years," the former Ireland and British and Irish Lions fly-half added.
In the other semi, 14-time champions Stade Francais face Bordeaux, playing 10km (6.2 miles) north of their Stade Chaban-Delmas home.
Parisians Stade Francais return to the last four nine years on from their last appearance having led the standings for half of the regular season.
"The objective was the top six," their director of rugby Laurent Labit told AFP.
"We're a historic club, a great club, who should be playing knockout games at the top of the table.
"We want to be able to play for titles every year," the former France attack coach added.
