Philipp Kohlschreiber upset second seed Marin Cilic 6-4 6-4 to advance to the last 16 of the BNP Paribas Open at Indian Wells on Tuesday.
Cilic, runner-up at this year's Australian Open, only managed to put 51 per cent of his first serves in play and was unable to convert any of his four break-point opportunities as the German recorded his seventh victory over Cilic in 11 career meetings.
The tournament's No 31 seed will next face Frenchman Pierre-Hugues Herbert, who advanced earlier on Tuesday after his countryman Gael Monfils was forced to retire from their match due to back pain.
Juan Martin del Potro made it five straight wins over tenacious Spaniard David Ferrer to advance to the next round in the Californian desert.
The sixth seed continued his fine start to 2018 after victory at the Mexican Open in Acapulco last weekend with a hard-fought 6-4 7-6 (7-3) success in one hour and 46 minutes.
"I beat a great fighter [in Ferrer]," said Del Potro, who will take on fellow Argentine Leonardo Mayer in the next round, after he cruised to a 6-4 6-1 victory over Japan's Taro Daniel. "I'm so glad to beat one of the tougher guys on tour.
"I need to play even better than today [against Mayer]. He's a good player. We know each other well, he's a friend of mine, so it's going to be a special match to me but I will try to do my best."
You can watch the ATP Masters 1000 from Indian Wells on Sky Sports Arena and via the red button from 6pm on Wednesday. You can also watch it on Sky Sports Main Event.
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