Andy Murray was ousted from the BNP Paribas Open in the quarter-finals after Juan Martin Del Potro fought back from a set down.
Murray, playing his seventh-seeded opponent for the first time since 2009, had edged a first-set tie-break but slipped to a 7-6 (7-5) 3-6 1-6 defeat as the heat took its toll and frustration set in.
The Scot would have overtaken Roger Federer as No 2 in the world rankings had he made the final in Indian Wells but instead he suffered only a second defeat in seven meetings with the Argentine player.
Del Potro broke early in the second set and repeated the trick in the decider, before saving a break point in a nervy fourth game to secure what proved a crucial hold.
He broke again en route to a 5-1 lead and was handed the match when Murray, on his rival's second match point, double-faulted for the eighth time.
After suffering defeat in two hours and 32 minutes, Murray said: "It was a tough match. He played like someone that's won a lot of matches recently.
"It was very hot; there were a lot of long rallies. Sometimes if your legs are just a little bit tired you can miss serves.
"The timing might go off a little bit and you're not quite getting up to them. That's maybe what happened today."
The Scot will now head to Miami in the United States for the Masters event that gets going next weekend.