But the American legend has warned it will take another big shock to stop favourite Sloane Stephens in their Paris match on Tuesday.
The British No.1 has raced from winning her first ever match here in the opening round to reaching the last eight. If she beats the 2017 US Open champion today, she will face either No.31 seed Petra Martic or world No.38 Marketa Vondrousova for the chance to reach her first ever Grand Slam final.
Few could have predicted such a change in Konta’s clay-court fortunes. Certainly not the 18-time Grand Slam singles champion.
“It came out of nowhere really,” said Navratilova. “Maybe she expected it but we really didn’t see it because she had never won a match here. Then she gets to the final of Rome which gives her a lot of confidence and she has backed it up here.
“Clearly she can play on any surface – she has got a nice game for anything. Maybe she didn’t surprise herself but she has certainly surprised us.”
Konta has benefitted from leading the GB Fed Cup team to two victories this season – and working with coach Dimitri Zavialoff who has encouraged a freer approach on all surfaces.
“I think she was always a good player – I would even say a fantastic player – and that’s what I keep telling her,” said the Frenchman.
“It’s just showing her how good she is and to invite her to try. To try and miss sometimes and sometimes try and achieve something.”
The Anglo-American clash will be first on Court Philippe-Chatrier with the Swiss derby between Roger Federer and Stan Wawrinka relegated to the second main court.
“Overall I am in a good place, enjoying my tennis, enjoying the opportunities,” said Konta.
“It’s an incredible position to play in one of the most beautiful stadiums in the world against a tough opponent. It will be 50/50 and I will be just be doing my best to edge the odds in my favour.”
Stephens is engaged to Jozy Altidore, the USA striker who was also better known for his misses during spells Hull and Sunderland. Last year’s runner-up here is luckily more accurate with her tennis shots although Konta has won their two meetings this season, including on the clay in Rome.
“She’s been playing much better on the clay but I’m just going to go in with a clean slate,” said the world No.7. “In a Grand Slam, playing for a semifinal there’s a lot on the line.”
Navratilova added” “I think it is a little early to be talking about Jo winning the title – you have got to get to the finals first. But she has got the game. Sloane is the favourite in this match– she is a better clay-court player, won a Major all of that. Yet on a given day, Jo can bother anybody. It is a matter of stringing it together for seven matches – that is the trick in a Major.”