The second round of action at the BNP Paribas Open will wrap up on Day 4, with seeds including defending champion Paula Badosa, Leylah Fernandez, Aryna Sabalenka and Ons Jabeur all getting their campaigns underway. Here are six matches to circle on the schedule.
 Paula Badosa (ESP) vs. Tereza Martincova (CZE)
It was only five months ago that Badosa launched herself into the Top 10 by winning Indian Wells, and the Spaniard already has to defend the biggest title of her career to date. (Her points will remain on her ranking for a full 12 months, though.)
There's been little sign of any drop-off as the 24-year-old has consolidated her new status. A semifinal run at the WTA Finals Guadalajara and a third career title in Sydney to start the year helped bump Badosa into the Top 5 for the first time. Early defeats in both Dubai and Doha didn't quite meet expectations, though neither Elena-Gabriela Ruse nor Coco Gauff should be considered a bad loss.
A stern test of how much Badosa has improved will come off the bat. Tereza Martincova's smooth striking and smart placement have all come together over the past year. She reached her first WTA final in Prague last July and made her Top 40 debut last month. Moreover, Badosa has yet to win a set from Martincova in three previous meetings, all prior to Badosa's breakthrough 2021 season.
Martincova has four career Top 20 wins under her belt, with the most recent being a marathon upset of Elina Svitolina in Doha. She is looking for her first Top 10 win.
Head-to-head: Martincova leads 3-0, all in straight sets. She won in Acapulco qualifying in 2018 (on outdoor hard courts), the 2019 Essen ITF W25 final (on clay) and in Ostrava qualifying in 2020 (on indoor hard courts).
 Leylah Fernandez (CAN) vs. Amanda Anisimova (USA)
Even though Fernandez and Anisimova are only a year apart in age, their career trajectories have already diverged significantly. US Open finalist Fernandez is still surfing the wave of her first major breakthrough. The 19-year-old Canadian put a disappointing Australian swing firmly behind her to successfully defend her Monterrey title last week.
Anisimova is just 20 but is already falling into the "resurgent" category. The American hit a career high of No.21 in October of 2019 after reaching her first major semifinal at Roland Garros that year but fell to No.86 last August. Anisimova started 2022 with an eight-match winning streak, including her second career title at Melbourne Summer Set 2 and a third-round upset of Naomi Osaka at the Australian Open. She appears to be taking joy in her tennis once again.
Fernandez and Anisimova have never played at any level. In terms of matchup, it will be fascinating to see Anisimova's clean power pitted against Fernandez's ability to redirect the ball and work the angles of the court.
Jasmine Paolini (ITA) vs.  Aryna Sabalenka
Credit to Sabalenka for how swiftly she's halted the narrative of the yips. She served an alarming 130 double faults over the course of eight matches at the WTA Finals and in Australia but reduced that number to 15 in her two Dubai matches and just seven across three contests in Doha.
Sabalenka still needs to properly kickstart her season, though. She has a 6-5 record in 2022 and has not reached a semifinal since a heartbreaking loss to Leylah Fernandez at that stage of the US Open. Paolini could be an interesting matchup, despite their contrasting physiques. The 5-foot-3 Italian also favours a hyper-aggressive game, which paid off in capturing her maiden title in Portoroz last September and making her Top 50 debut this year.
Head-to-head: 1-1, with Paolini winning a third-set tiebreak on grass at the 2017 Ilkley ITF W100 event and Sabalenka taking their 2020 Linz first round 6-4, 6-4.
 Maria Sakkari (GRE) vs. Katerina Siniakova (CZE)
Few who saw Siniakova's 7-6(5), 6-7(8), 6-3 defeat of Sakkari in the second round of Roland Garros 2019 will forget that 3-hour, 14-minute rollercoaster ride of scoreboard fluctuations, match-point saves and 14 service breaks. The Czech backed it up with an upset of Naomi Osaka in the next round, but since that tournament it's Sakkari whose rise has steadily continued.
The Greek reached two Grand Slam semifinals in 2021 to lay the foundations for a Top 10 debut. While the later rounds of tournaments are still something of a barrier for her, she continues to be adept at reaching them in 2022. Sakkari comes into Indian Wells off the back of the Australian Open fourth round, the St. Petersburg final and the Doha semifinals.
By contrast, Siniakova is frequently involved in superb battles against top players and can never be counted out to pull off an upset, but her talent hasn't translated into many match wins lately. Her three-set defeat of Irina-Camelia Begu in the first round was her first in a WTA main draw this year.
Head-to-head: 2-2. They have played each other at every major, with Sakkari winning at Wimbledon 2017 and the 2021 US Open, and Siniakova triumphing at the 2018 Australian Open and Roland Garros 2019.
Naomi Osaka (JPN) vs.  Veronika Kudermetova (RUS)
After a thrilling three-set win in a marquee first-round match against Sloane Stephens on Thursday, Osaka now faces a Top 30 opponent for the first time since defeating Coco Gauff in Cincinnati last August. The 2018 champion Osaka was due to face Kudermetova in the Melbourne Summer Set 1 semifinals in January but withdrew due to an abdominal injury.
Kudermetova, whose strong singles results in the first half of 2021 were overtaken by her doubles success in the second half, has got back on track in the former in 2022, adding a second final run this season in Dubai.
[Q] Daria Saville (AUS) vs.  Ons Jabeur (TUN)
Last November, Jabeur was something of a revelation in the Californian desert. During the Tunisian's run to the Indian Wells semifinals, her renowned touch proved a perfect fit for the conditions, not least in her ability to use the wind to her advantage. After being forced to withdraw from the Australian Open due to a back injury, Jabeur bounced back to deliver a pair of quality quarterfinal runs in Dubai and Doha.
The former World No.20 Saville's comeback is still in its early days, but following a Guadalajara quarterfinal by qualifying here and defeating Zhang Shuai 6-3 6-2 in the first round bodes well for the Australian. Her ranking is still down at No.409, but she's operating at a much higher level.
Head-to-head: 1-1, with Jabeur winning 6-4, 6-0 in the 2013 Baku first round and Saville coming through 1-6, 6-4, 6-3 in the 2018 Charleston first round.
Click here to view the full Day 4 order of play.