Roger Federer played superbly to claim a third straight win over Rafael Nadal for the first time in his career and reach the last eight in Indian Wells.
The Swiss, 35, won 6-2 6-3 to follow up his Australian Open final victory over the Spaniard two months ago, when Federer won his 18th Grand Slam title.
He will next face Australia's Nick Kyrgios, who upset world number two Novak Djokovic 6-4 7-6 (7-3).
Svetlana Kuznetsova was the first player into the women's semis.
The eighth seed saw off fellow Russian Anastasia Pavlyuchenkova 6-3 6-2 and will meet Czech third seed Karolina Pliskova, after she beat Spain's French Open champion Garbine Muguruza 7-6 7-6.
Aggressive Federer crushes Nadal
In the pair's 36th meeting - and first before the quarter-finals of a tournament since their initial meeting in Miami 13 years ago - Federer notched his 13th victory and third in a row.
Nadal, 30, had built his success against Federer over the years on attacking the Swiss player's backhand, but Federer turned his weaker wing into a weapon in the Australian Open final, and if anything was even more aggressive in Indian Wells.
Federer crunched six backhand winners to none from Nadal as he played a flawless opening set, taking it in a little over half an hour.
Nadal might have hoped to profit from a surface markedly slower than that in Melbourne but it did nothing to curb Federer's aggressive intent.
Another early break in the second set had Federer within sight of the finish line and he raced through with four breaks of serve to none to win in 68 minutes.
"I did very well today, I'm so pleased I'm able to step into the court and play super aggressive," said Federer. "Coming over the backhand has been part of that.
"It's a nice feeling to win the last three, I can tell you that. But most importantly, I won Australia. That was big for me.
"For me, it was all about coming out and trying to play the way I did in Australia. I didn't think it was going to be that possible, to be quite honest, because the court is more jumpy here so it's hard to put the ball away."
Djokovic helpless against Kyrgios serve
Kyrgios, 21, gave further evidence that he is now a force to be reckoned with as he blunted the Djokovic return game with another magnificent serving performance.
Djokovic, 29, was on a 19-match winning streak in the Californian desert, and bidding for a fourth consecutive title, but Kyrgios took their personal head-to-head to 2-0 as he repeated his victory in their first meeting in Acapulco 12 days ago.
Just as he had in Mexico, Kyrgios gave the Serb nothing to work with as he powered through without facing a break point in nearly two hours.
The Australian grabbed the only service break of the match in the opening game, which proved enough to take the first set, and clinched the second after racing into a 3-0 tie-break lead.
"I am serving really well, that is creating chances for me to put pressure on their service games," said the 15th seed.
"My mentality is improving and I am trying really hard to fight for every point and just compete."
Djokovic praised the Australian's serve, adding: "Nick, again, as he did in Acapulco, served so well. I just wasn't managing to get a lot of balls back on his serve, first and second, as well. That's what made a difference."
Japan's fourth seed Kei Nishikori swept past American Donald Young 6-2 6-4, while on the other side of the draw Spanish 21st seed Pablo Carreno Busta and Argentine 27th seed Pablo Cuevas progressed to the quarters.
American 17th seed Jack Sock battled past Malek Jaziri of Tunisia 4-6 7-6 (7-1) 7-5.
Austrian eighth seed Dominic Thiem eased past France's Gael Monfils 6-3 6-2. Thiem will play Switzerland's Stan Wawrinka, after the three-time grand slam champion, laboured for two hours and 13 minutes to get past world number 70 Yoshihito Nishioka, winning in three sets 3-6 6-3 7-6.
Good day for the Murrays
Fourth seeds Jamie Murray and Brazilian Bruno Soares made it through to the doubles semi-finals with a 7-6 (7-5) 6-4 win over Dutchman Jean-Julien Rojer and Romania's Horia Tecau.
And despite his absence following a shock early exit, Andy Murray saw his position at the top of the rankings enhanced after Djokovic's defeat.
The Serb lost 990 points as he fell well short of defending his title, while Murray's relatively modest record in Indian Wells meant his early loss only cost him 20 points.
Djokovic will also be defending a title later this month in Miami - another tournament where Murray lost early in 2016.