Simona Halep  v Iga Swiatek 
It feels a little disrespectful to consider Simona Halep as part of the old guard, but as two Grand Slam champions face off in the first of the semi-finals, it feels like we are seeing Halep return to the kind of form that kept her a constant presence at the top for many years.
Over the net is Iga Swiatek, who has been undefeated in WTA 1000 level events this year, and her utter destruction of Madison Keys in the quarter-finals for the loss of just one game and was a stark contrast to her earlier matches where she had to come back from a set down in all of her previous rounds. The Pole is on a nine-match winning streak and looking to continue her best run so far at Indian Wells.
Halep also raced through her quarter-final in her quickest match of the tournament so far, but is 0-2 at this stage of the tournament. With all the injury issues she has had to overcome since last year, this feels like a real resurgence, and actually leads the head-to-head 2-1, all at the later stages of Slams.
Experience plays youth, but how true can that be when Swiatek scooped her maiden Slam while still a teenager, and is currently in devasting form on the hard courts right now.
Paula Badosa  v Maria Sakkari 
Maria Sakkari has steamed through this tournament, including taking out Petra Kvitova but she needs to overturn a 4-15 record in semi-finals if she wants to give herself the best chance of a big leap in the rankings.
But all eyes will be on Paula Badosa who wants to be the first woman in over 30 years to defend her title in the desert. She overcame a losing record over Veronika Kudermetova in what was her most convincing match of the week, to book her spot in the semi-final.
She leads the head-to-head over Sakkari 1-0 when the pair made their debut at the WTA Finals, and both have been in very good form since the start of the year, but it is Badosa who has already been able to add silverware to her collection this year, starting the year off with the Sydney title.
Not surprisingly, this is a lot tighter in the odds, but there are plenty of options to choose from with bet365.