The 38-year-old surpassed former fly-half rival Ronan O’Gara as his country’s all-time leading scorer by moving on to 1,090 career points during Saturday’s emphatic 59-16 win over Tonga.
Sexton last week returned with a bang from almost six months on the sidelines to leapfrog O’Gara as Ireland’s top points scorer at the Rugby World Cup, in addition to becoming the oldest international to wear the green jersey.
His greatest challenge following his long-awaited comeback from injury and suspension undoubtedly lies ahead, with the tantalising Paris showdown against the Springboks likely to decide who tops Pool B.
“The proof of whether I’m in good form will be next Saturday,” said Sexton, who will retire after the tournament. “You’ve got to go and do it in the games.
“There’s no point in saying you’re feeling good or whatever. I just take it day by day, make sure I recover well, turn up to training on Monday and Tuesday and try and put the plan in place to take on the reigning world champions.
“They’ve hit a great vein of form and it’s going to be a huge challenge for us but one that we are really excited about and we feel we’re ready for it.”
Sexton claimed the fourth of Ireland’s eight tries on a history-making evening in Nantes.
He also kicked four conversions and a penalty to add to the 24-point haul he managed in the curtain-raiser against Romania before being withdrawn at half-time.
Bundee Aki’s second-half double, in between scores from James Lowe and Rob Herring, helped seal Ireland’s 15th successive win after Tadhg Beirne, Caelan Doris and Mack Hansen laid the foundations.
While Scotland will still hope to have a say, Ireland and South Africa lead the way in the group, with the eventual table-toppers likely to avoid hosts France and play New Zealand in the quarter-finals.
“Obviously we want to win the group,” said Sexton. “We want to win every game. That’s pretty clear.
“If you get through the group, it doesn’t matter if you finish first or second, you won’t have an easy game.
“But we’ll be going for the win next week and hopefully the game after (against Scotland) as well.”
Andy Farrell’s decision to name a strong starting XV at Stade de la Beaujoire was vindicated by a second successive bonus-point triumph from which his team emerged relatively unscathed.
The head coach, who was upbeat about replacement prop Finlay Bealham’s head injury assessment, hopes his players can move up gear in the capital in six days’ time.
“I would hope we will be better because we’ll certainly need to be when it gets to playing against a fantastic side in South Africa,” he said.
“But two games under the belt is good for us. Hopefully that rolls on to to another level on the third week.
“This is what World Cups are all about, weeks that are coming against the reigning world champions.
“It doesn’t get any better and one thing’s for sure, you know that the Irish (fans) are going to turn up and enjoy it as well. It’s a fantastic week to look forward to.”