Stephens has had to battle back from a foot operation which left her unable to walk for four months.
"Indoors on a hard court". "It has been a long time without good feelings".
Less than a year later, she is on the verge of becoming a two-time Grand Slam victor and will peak at a career-high No. 4 in the WTA leaderboard after a splendid run at Roland Garros.
Indeed, her Roland Garros campaign this year came close to ending in the third round when Italy's Camila Giorgi twice served for the match and was within two points of winning.
'It's a big opportunity, it's a big chance, but you never know, ' she said after beating Muruguruza.
Muguruza, a two-time major champion, entered the semifinals having not lost a set in the tournament. Their French Open quarterfinal on Wednesday (Thursday NZ Time) was no contest at all, a 6-2 6-1 one-way journey.
But Keys, who made 23 unforced errors in the first set, hit back hard and set up a break point at 3-2, only for Stephens to save it with a service return victor.More news: Investors seek economic policy details after Conservatives win Ontario election
While the Romanian sometimes has trouble with so much on the line, Stephens has been ideal in title matches on the WTA tour, going 6-0.
'And, I mean, there is no formula.
"I'm going to have to be the one to try to open up the court and go for my shots". I'm not trying to break a record.
"I don't want to think about that because, as I said many times, it's a different match, different situation".
But I also think Stephens has figured out the awkward dynamic of playing your good friend better than Keys has. Stephens has made the second week in Paris in five of her seven appearances and Keys is slowly coming to terms with the surface.
Stephens hasn't dropped a set since. "And I think when you make it out of that, you build a little bit of confidence". I think Stephens has been too consistent throughout these two weeks.
The American pair have contrasting styles, with Stephens' game based on her athleticism and ability to get many balls back, while also turning defence into offence fairly quickly. There are always going to be times when it's really tough, and there will be times when you're on an extreme high.
This will be the world No. 1's fourth major final and her second trip to the last stage at Roland-Garros in as many years, having suffered a shock defeat at the hands of then-teenager Jelena Ostapenko in 2017. I'm more relaxed about this situation", Halep said, sounding convinced of her words as they hung in the air, until she added this: "But you never know. "If I do that, I will be OK after the match, no matter the result".
"Both of them are similar in the sense that if you can get them off of the baseline, then you can open up the court", Keys said. Now she gets her fourth chance to do exactly that.
Halep is still chasing her first Grand Slam title.