Chilean Cristian Garin's aggressive play overwhelmed Casper Ruud at Indian Wells on Sunday as the qualifier upset the third seed 6-4 7-6(2) to book a spot in the last 16.
Garin pounded 27 forehand winners and fought off a second set comeback attempt to dispatch the struggling Norwegian, who has yet to win consecutive matches this season.
"I'm so happy with the way that I played," said Garin.
"I played so aggressive the whole match, even in the second set when I was leading 3-1 and lost those games."
With the win Garin, a former top 20 player now ranked 97th, improved his career record against Ruud to 3-1.
"Casper is one of the players I really, really like on the tour so it's very special to me," said the Chilean.
Ruud is still searching for the sensational form that saw him make the finals of the French Open and US Open and soar up the rankings last year.
Garin will next face Spaniard Alejandro Davidovich Fokina who beat Russia's Karen Khachanov 6-3 1-6 6-4.
German 12th seed Alexander Zverev dug deep to beat Emil Ruusuvuori 7-5 1-6 7-5 despite admitting he was not at his best.
"To be honest I thought he played much better than me throughout the match," said Zverev.
"That's just the way it is sometimes... This is tennis, one or two points can decide a match and I'm happy that I won those points."
Zverev will next face red-hot Russian Daniil Medvedev, who continued his recent streak of dominance that led to three consecutive titles with a 6-2 3-6 6-1 win over Belarusian Ilya Ivashka.
Fifth seed Medvedev looked like he would make quick work of Ivashka after a one-sided first set but ran into trouble in the second where he grew agitated with some noisy fans on a windy night on center court.
He corrected course in the third, however, breaking to take a 2-0 lead and cruising to the finish.
Earlier in the day Britain's Cameron Norrie, seeded 10th, fought back to beat Japanese player Taro Daniel 6-7(5) 7-5 6-2 as the 2021 champion looks to add a second Indian Wells title to his collection. He will next play Russian sixth seed Andrey Rublev.
American Frances Tiafoe, seeded 14th, will face Chilean Alejandro Tabilo in the round of 16 after both players advanced in straight sets.
Sakkari survives
On the women's side, seventh-seeded Maria Sakkari of Greece kept her title hopes alive by battling back to beat Ukrainian Anhelina Kalinina 3-6 6-2 6-4.
Sakkari drew Kalinina to the net with a drop shot and then fired a backhand winner down the line on match point to complete the comeback.
The Greek leaned over and pumped her fists in celebration after sealing the win on a hot day in the Southern California desert.
"I don't mind winning ugly," she told reporters.
"It doesn't really matter. I just give myself another chance to play better the next day."
Sakkari, a finalist in Indian Wells last year, will next face 17th seed Karolina Pliskova in the round of 16 after the Czech beat Russia's Veronika Kudermetova 6-1 7-5.
Third-seeded American Jessica Pegula edged Russia's Anastasia Potapova 3-6 6-4 7-5 to set up a meeting with Petra Kvitova after the 15th-seeded Czech won a rollercoaster match against Jelena Ostapenko 0-6 6-0 6-4.
Sweden's Rebecca Peterson dispatched Jil Teichmann of Switzerland 3-6 6-3 6-1, 16th seeded Czech Barbora Krejcikova beat China's Wang Xinyu 6-2 7-6(1) 6-2, and sixth-seeded American teenager Coco Gauff beat Czech Linda Noskova 6-4 6-3.
Belarusian second seed Aryna Sabalenka advanced via walkover when her Ukrainian opponent Lesia Tsurenko withdrew.
