Murray reaches Miami final

The fourth seed had looked set for another comfortable night's work under the lights in Miami when he cruised through the opening set in just over half an hour. But Del Potro again proved his mettle to take just the second set off Murray at this year's event and level the match. The 20-year-old's energy-sapping three-hour battle with Rafael Nadal on Thursday, however, seemed to bite in the decider as Murray closed it out in two hours and 17 minutes.

Murray will now meet Novak Djokovic in Sunday's final after the Serbian upset Roger Federer 3-6 6-2 6-3 earlier in the day. Djokovic's win means Murray will be unable to pass him into third place in the world rankings, but victory in the final would move him closer to achieving that feat.

The Scot had lost just four games in his previous two wins against Viktor Troicki and Fernando Verdasco, when on both occasions he set the tone by immediately taking a double break of serve. He would replicate that against Del Potro to again assert his authority over the contest and race into a 5-0 lead. After cruising through his opening service game, Murray got his opening break after twice saving game points in a 10-minute battle he eventually settled with a forehand down the line. His second break of serve came far easier, this time after taking into a 15-40 lead.

While Murray needed to use the the second break point to take the game he did so in signature style - successfully chasing down a seemingly lost cause which Del Potro duly dumped into the net from inside the service box. The match was quickly mirroring Murray's 6-1 6-2 demolition of Verdasco 24 hours earlier when the Scot frustrated his opponent simply by retrieving so many balls.

Del Potro was succumbing in a similar vein, repeatedly overhitting shots either long or into the net, as he tried to find a way past his fleet-footed opponent. The sixth-seeded Argentine did finally get on the scoreboard with 32 minutes played, to make it 5-1, but Murray then held comfortably to close out the opener 6-1.

With a certain sense of inevitability overcoming the match, Del Potro had to find answers to Murray's dominance and did so effectively to win the opening two games of the set. The 20-year-old's first-service radar had been off in the opening set but he rediscovered it to take the first game before breaking Murray - who double faulted to give him the chance - in the next.

The break lasted just five minutes, however, as Murray tenaciously clawed back the advantage - Del Potro reacting with an animated show of frustration. The Argentine, however, looked determined not to let his win against Nadal go to waste and opened up a 0-30 lead in the next game on Murray's serve. But unlike Nadal on Thursday, Murray looked eager to meet every challenge and reeled off the next four points to level the set at 2-2.

The games then went on service, Del Potro ominously twice winning his service to love, until the 12th game when Murray failed to win a point on serve to concede the set. The third set was a far more cagey affair before Murray got the decisive break in the fifth game. Del Potro showed signs he was feeling the after-effects of his game yesterday when he pushed a forehand wide before calling for a hopeful review of the call, seemingly more out of a need to recapture his breath than in expectation. He duly lost his appeal and a tired backhand into the net on the next point conceded the break.

Murray quickly won his next service and had another break point to go 5-2 up when Del Potro took a three-minute medical time out. It only delayed the inevitable as Murray got the double break before serving it out to love - his winning shot a backhand down the line.