After an impressive victory over Taro Daniels in the opening round, Andy Murray's time in Indian Wells was cut short by world No.33 Alexander Bublik.
Murray's win over Daniels marked the 700th victory in his career, but his run came to an end on Sunday evening after an error-strewn performance.
The two played out a thrilling first set, where Murray failed to take advantage of three set points before faltering in a tie-break.
Two failed break points in the opening game of the following set added to the Scot's frustrations, and Bublik's break in the fourth game set him on his way to victory.
Back under former coach Ivan Lendl, Murray showed heart in the final game of the second set, digging deep to deny three break points.
But in the end, the 34-year-old was left regretting his missed chances as Rublik closed out a 7-6(9) 6-3 victory to reach the round of 32.
Following the defeat, Murray was left devastated over a number of missed opportunities.
"Both of us had some chances in the tie-break, but in the first set I certainly created more of the opportunities and I didn't take them," he said.
"He obviously came up with some good serves at times, but I certainly had my chances and against players that play that style of tennis and have obviously big serves and are not easy to break, you need to be ruthless when you get your chances and I just didn't quite play well enough in those moments today."
As for Rublik, the Russian-born star will face Grigor Dimitrov for a place in the final 16, with the pair set to take to the court on Tuesday evening.