By Andrew Friedman

NEW YORK—Don’t quote Andy Murray the old expression that "it doesn't matter whether you win or lose; it’s how you play the game." His philosophy is exactly the opposite.

Ten days ago, Murray had an epiphany while observing the US Open’s opening night red carpet parade of champions. As the greats of the game marched along, the Scot realized that "winning is what really, really counts."

Murray applies that not only to the span of history but also to individual matches."I don’t care what happens throughout the course of the match, as long as I win," he said after beating Argentine Juan Martin Del Potro 7-6 (2), 7-6 (1), 4-6, 7-5 to reach the semifinals of a Grand Slam for the first time.

One could be forgiven for wondering whether Murray would prevail against fellow boy of summer Del Potro. The Scot was coming in as the No. 6 player in the world, but his 19-year-old opponent had arrived in Flushing on a tide of invincibility after winning 23 straight matches and four straight tournaments (Kitzbuhel, Stuttgart, Washington, and Los Angeles). What's more, del Potro had looked fearsome as he walloped one brutal groundstroke after another in his fourth-round romp over fellow up-and-comer Kei Nishikori.

Unsurprisingly, Murray seemed intent on not giving his potentially overpowering opponent anything—no pace, no rhythm, and no predictability. The tactic was apparent from the first point, on which Murray hit a delicate drop-shot winner. He went on to slice and loop balls back to the lanky Argentine, varying not just spin, but also depth and pace, racing out to a 3-0 lead. Though Murray generally succeeded with these tactics—including the repeated and successful use of a drop shot-lob combination—he handed back breaks in the first and second sets and had to salvage both in tiebreaks. For long stretches, it appeared that his biggest opponent wasn’t Del Potro, but his own inconsistency, as slices drifted wide and routine backhands died in the center of the net. Afterwards, Murray offered that it was gusty on the south end of the court, where he produced the most unforced errors.

But Murray also professed to be perfectly happy with the topsy-turvy affair that ultimately lasted a hair under four hours, saying that he fought well on the big points and came away with the all-important win.

Winning clearly means a lot to his opponent as well: Del Potro called for the trainer repeatedly, emerging from one treatment with tape on his knee and hamstring, but continued to fight. Though Labor Day had already come and gone, he wasn’t ready for his dream summer to end. He played a gutsy return game to break Murray at 4-all in the third set, then served it out. He also earned a break at 3-all in the fourth, and the suddenly surging Argentine seemed bound for an improbable fifth set. The crowd got behind him, but by then, he was walking stiffly and grasping his inner right thigh between points. Murray broke back, then broke again at 6-5 to take the match.

Del Potro hadn’t suffered a loss since June, and during his post-match question-and-answer session with the Spanish-speaking press, he became emotional, tearing up and leaving the room briefly to regain his composure.

Asked about the episode, Murray observed that winning can be a double-edged sword: "I think when you’ve been on a run like he has, I guess when it ends it’s pretty emotional because—and it’s pretty tiring as well to keep winning matches like that…that’s what makes sort of Federer and Nadal’s achievements unbelievable because of how tough it is to keep doing that."

Clearly, Murray would relish the challenge himself. "I’m excited to be in the semifinals," he demurred when asked about his implacable expression after the match, "but the tournament is still going."

Murray’s done a fair amount of winning this year – titles at Doha and Marseille, and his first-ever Masters title at Cincinnati last month. Asked about remaining goals for 2008, he said he wants to qualify for the year-end Masters Cup in Shanghai and believes that he’s all but "confirmed" himself among the final eight who will qualify for the event. It seems a safe bet that by the time he gets there, he’ll have amended the mission to not just participating, but winning.