So, Andy Murray will not become the world number two - he would have if he reached the final in Indian Wells - and Del Potro will now play Novak Djokovic in the semis.
Andy Murray - Juan Martín Del Potro
Indian Wells Masters - 15 March 2013
Indian Wells – Follow the Tennis match between Andy Murray and Juan Martín del Potro live with Eurosport. The match starts at 20:30 on 15 March 2013. Our live coverage lets you follow all the key moments as they happen.
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MURRAY 7-6 3-6 1-6 - GAME, SET & MATCH! Murray's just not himself. Another weak effort into the net and he's 15-30 down before another double fault brings up a pair of match points for Del Potro. The first one is saved by a forehand winner from the racquet of Murray but an eighth double fault of the match gifts victory to the Argentine!
MURRAY 7-6 3-6 1-5 - JMDP serves up his first double fault of the match at 30-0 up but he hits back with a tremendous leap to reach what looked to be a great Murray lob. He smashes back past the Scot before taking his foot off the gas a little to allow Murray back into the game at deuce. But the world number three plays a pair of loose shots though and the game is JMDP's!
MURRAY 7-6 3-6 1-4 - BREAK! Murray finds himself in more bother as he drops to 0-30, but the Scot channels his frustration into a blistering forehand crosscourt winner on the next point. He can't maintain that momentum though and an attempted forehand down the line brings up break point for JMDP soon after. Murray goes long and Del Potro has a double break!
MURRAY 7-6 3-6 1-3 - Del Potro wastes his final challenge in blowing a double hold point, Murray nets from deuce but JMDP mis-hits a drop shot attempt. He finally holds on deuce three, to avoid a break-back in one of his worst service games so far.
MURRAY 7-6 3-6 1-2 - BREAK! - Now Del Potro mirrors the last game by creating his own break point. Murray serves up deuce but the Argentine follows with another break point from there and this time he makes it count.
MURRAY 7-6 3-6 1-1 - A break point for Murray but Del Potro does well under the pressure to leave the Scot no chances to make good on it. He holds from deuce.
MURRAY 7-6 3-6 1-0 - After two sub-par opening service games in the first two sets, Murray finally gets it right this time. He only holds to 30 but that's credit to Del Potro's returns. The clinching point a belter as the two trade seemingly-finishing shots before Muzza finally forces Juan Martin out of boundaries.
MURRAY 7-6 3-6 - SET! Del Potro weathers a great point from Murray for 15-15 with more supremely confident service and we are going to a third set!
MURRAY 7-6 3-5 - Murray wins a lovely little drop-shot duel to go 30-0 up on his way to a hold to love. But nonetheless, Del Potro will now serve for the second set.
MURRAY 7-6 2-5 - Murray seems to be in a consistently bad mood. If not the sun in his eyes, it's squabbles over what he sees as frivolous challenges from his opponent. Either way, Del Potro overcomes early wobbles to hold and he's one game away from 1-1.
MURRAY 7-6 2-4 - Murray flirts with a double-break on more than one occasion but is able to snatch the hold from deuce. The sun is dying down over the stadium now so perhaps that will allow Andy, who has jettisoned his cap, to get back into his groove.
MURRAY 7-6 1-4 - Del Potro keeps his serve strong and remains on course to tie this up. It's been almost a different Juan Martin in this set. Not to say he was playing badly in the first, but those openings in Murray's game were there to exploit before and now he is going for it.
MURRAY 7-6 1-3 - Andy gets his first game of the set on the board, and comfortably so. But he has it all to do still if he's to avoid a decider.
MURRAY 7-6 0-3 - Murray stops the rot at nine points, returning twice for 30-15. But Del Potro gets back on top with three aggressive serves and the Argentine is looking strong early in the second.
MURRAY 7-6 0-2 - BREAK! - Well, how about that. First break of the game and it's to love. Del Potro with all eight points in the set so far. Murray cutting a frustrated figure.
MURRAY 7-6 0-1 - For as long as the first set was, Del Potro holds to love in the second set opener in less than a minute. The sun very much remaining an issue for the players, caps or no caps.
Five Murray aces to Del Potro's zero, in a set which lasted 10 minutes longer than Djokovic-Tsonga in its entirety.
MURRAY 7-6 - SET! - Despite a cracking forehand to make it 2-2, Del Potro drops the next three points, including two on serve, as Murray draws him into arduous rallies. The Argentine reduces the gap to 5-4 as Murray nets under zero pressure but a magnificent 43-shot rally gives Murray two set points. Del Potro rescues one but goes wide on the second and after 64 minutes, Murray takes the opening set!
MURRAY 6-6 - Though Andy can smell victory in the set as he pushes for 30-30, Del Potro holds on from there and it's time for a tie-break.
MURRAY 6-5 - Too much pace on the serve for Del Potro to deal with and he's brushed aside to love in game eleven. Can't see this going any other way but a tie-break, however.
MURRAY 5-5 - Del Potro withstands a Murray fightback from a triple hold point for game-30. Some great counter-attacking from Muzza but it was too little, too late.
MURRAY 5-4 - Great pressure from Murray following up his serve gets him back into the land of comfortable holds. He serves to 15 and though a break has seldom looked likely in this set so far, the Olympic gold medallist can snatch the opener if he does so next.
MURRAY 4-4 - Del Potro responds in kind for the fourth time and it will probably take something special (or catastrophic) to avoid an opening set tie-breaker.
MURRAY 4-3 - After wrong-footing the Argentine with a crisp backhand, Murray loses out on a long rally for 30-30. But a curious unforced error from Del Potro and the Brit's fourth Ace of the match so far are enough for an uncomfortable hold.
MURRAY 3-3 - Curse of the (online) commentator perhaps as JMDP reponds with his own best service so far. Finely poised in the opening set.
MURRAY 3-2 - Murray's best service yet for a hold to 15. The current contrast says that Muzza is most likely to find that first break.
MURRAY 2-2 - Solid hold from Del Potro. Nothing massive separating the two in these feeling-out games.
MURRAY 2-1 - Better from Andy, though he's somewhat fortunate when Del Potro makes a hash of a backhand drop in the third point. The Argentine then returns one for 40-15 before Murray finally completes the hold.
MURRAY 1-1 - Del Potro certainly more comfortable in service, at least initially, and a hold to 15 keeps the opening set balanced.
MURRAY 1-0 - Del Potro finds it all too easy to return Murray's first few serves and has a double break point before too long. But the Scot times finding his feet well and powers home four straight points to rescue the hold.
Murray with first serve... and we're underway!
These two men last met at the 2009 ATP World Tour Finals. Murray won 6-3 3-6 6-2.
Nadal, Berdych, and now Djokovic. The winner of this fourth quarter-final will meet Novak in the semis to tomorrow.
Good evening and welcome to Eurosport's LIVE Indian Wells matchcast as Andy Murray and Juan Martin Del Potro battle for the final spot in the last four.