It's semifinal action with a historically strong lineup on Day 10 of the BNP Paribas Open. For the first time in the history of the tournament, the last four features three different reigning Slam champions -- Iga Swiatek, the Roland Garros and US Open title holder, Elena Rybakina, the Wimbledon champion and freshly crowned Australian Open titlist Aryna Sabalenka. Joining them is last year's Indian Wells runner-up Maria Sakkari.
The last time a WTA 1000 semifinal lineup included three reigning Slam champions was at Madrid 2015, where Petra Kvitova, Serena Williams and Maria Sharapova all made the final four. Swiatek's clash with Rybakina will be only the second time two reigning Slam champions have played each other at Indian Wells, following Martina Navratilova's 6-2, 7-6(6) defeat of Monica Seles in the 1991 final.
Either Swiatek or Sakkari could become the first player to reach consecutive Indian Wells finals since Sharapova in 2013. If both win, it will be the first time in the history of the tournament that the final has been contested by the same players in back-to-back years.
If Sabalenka defeats Sakkari and plays the final against either Swiatek or Rybakina, the tournament will be the first to feature two matchups of reigning Slam champions since Beijing 2019, when Naomi Osaka defeated Bianca Andreescu in the quarterfinals and Ashleigh Barty in the final.
More from Indian Wells: Scores | Order of play | The best of Week 1 | Sakkari 'surviving and finding ways' | Rybakina defeats Muchova | Swiatek sails into semifinals
 Iga Swiatek (POL) vs.  Elena Rybakina (KAZ)
Head-to-head: 1-1 (Rybakina leads 1-0 on outdoor hard courts)
Iga Swiatek is still the dominant World No.1. Just last month, she set an Open Era record for fewest games dropped en route to a tournament win (five in Doha). She has not dropped a set yet in Indian Wells. But a handful of players have found cracks in the Pole's aura of invincibility over the past few months, and Elena Rybakina is one of them.
Rybakina's 6-4, 6-4 defeat of Swiatek in the Australian Open fourth round was a statement that this matchup could be a key generational rivalry in the future. A rematch just two months later is an opportunity for Swiatek to respond -- particularly, to show that she's found some answers to the Kazakh's booming serve, which has tallied 140 aces this year already.
The last time two reigning Slam champions faced each other multiple times within three months was in 2017 when Jelena Ostapenko defeated Garbiñe Muguruza in the Wuhan quarterfinals. Muguruza avenged that result in the WTA Finals Singapore round robin.
Swiatek was cagy when asked about playing Rybakina again. She had watched her quarterfinal win over Karolina Muchova, but said:
"I didn't really watch a lot of what Elena did. I was more focused on what Karolina did, because I feel like she can play great tennis but because of her injuries she wasn't able to do that, and it's great to see her performing that well.
"Elena, I know she can play great tennis, I felt that on my racquet. I don't need any proof. I'll just be ready for tomorrow, and that's all."
Rybakina also sought to downplay her chances somewhat after needing 2 hours and 45 minutes to get past Muchova, her longest match of 2023 so far.
"It also depends a lot how physically I feel," she said. "I'm kind of realistic in these things."
Rybakina also pointed out the different, slower conditions in Indian Wells to Melbourne, and noted that she wouldn't be able to get away with any inconsistency.
"If it's gonna be a bit of a drop, like today in the second set when it was very quick [...] then of course the chances are less. There is not many margin to mistakes, I will say."
But the 23-year-old brings an underlying confidence to the matchup: "Of course, if I am gonna bring my best tomorrow, there are chances that I'm gonna win," Rybakina said. The pair split both of their junior meetings, and have now split both of their pro meetings.
 Maria Sakkari (GRE) vs.  Aryna Sabalenka
Head-to-head: Sabalenka leads 4-3 (3-3 on outdoor hard courts)
"I'm a little bit different player [this year]," Aryna Sabalenka said after her quarterfinal defeat of Coco Gauff. That result was a perfect example of the newfound calm Sabalenka says she now brings to the court.
Previously, Gauff had been a frustrating opponent for her. The American's counterpunching abilities had instilled uncertainty into Sabalenka's strokes. The pair invariably ended up embroiled in chaotic three-set rollercoasters, and Gauff had been the victor on three of four occasions.
This time, though, the brand new Australian Open champion was clear-headed as she executed a game plan of targeting the Gauff forehand with no let-up or dip in focus. Consequently, she needed only 64 minutes to race into her first Indian Wells semifinal, her third of the year, and extend her record to 16-1.
By contrast, Maria Sakkari has been the first to admit that she hasn't played her best tennis this fortnight. In her words, she's in the last four for the second year running by "just surviving and just finding ways." She's only the second player in tournament history to win four three-set matches to reach the semifinals, following Maria Kirilenko in 2013.
But even if Sakkari doesn't feel that her serve or groundstrokes are where she'd ideally like them, the grit she's shown to pull out those four wins has been top-notch, and a reminder of one of the Greek's crucial assets.
Now's where it's tended to get tricky for Sakkari, though. She's reached 26 tour-level semifinals in her career, and won only seven of them. She's fallen at this stage twice this year already, in Linz to Petra Martic and in Dubai to Jessica Pegula.
Sakkari does hold certain advantages in this matchup, though. Sabalenka may lead the overall head-to-head, but Sakkari has won all three of their matches in North America (Sabalenka has dominated in Asia and the Middle East). That includes their last two meetings at the WTA Finals in 2021 and 2022. Can Sakkari use the slow surface to her advantage and halt the Sabalenka steamroller?