SAN DIEGO, Calif., June 20 (Reuters) - One poor drive ultimately cost Louis Oosthuizen a chance of winning the U.S. Open at Torrey Pines on Sunday but the South African said he would probably take the risky shot on again if he was given the chance. A stroke behind Jon Rahm, who was already in the clubhouse, Oosthuizen could have hit a more lofted club off the tee for safety at the par-four 17th but decided it was time to take a calculated risk. "Slide, slide" the 38-year-old yelled as the shot headed for trouble, the ball drifting left into a hazard and an unplayable lie. Oosthuizen, who has now finished runner-up six times at a major, dropped a stroke at the hole and while he got it back with a birdie at the par-five 18th it was not enough. "I knew it was a crucial hole to take it on and give myself a birdie opportunity," said Oosthuizen, who shot an even-par 71 after starting the round in a three-way share of the lead. "I didn"t pull it off, but standing on that tee again, I would probably do the same thing, taking a driver and taking the shot on. "I went for it, and that"s what you have to do to win majors. Sometimes it goes your way, and other times it doesn"t." With his languid swing and unflappable temperament, Oosthuizen coped well over a difficult back nine and held his nerve on the greens, making a series of testing par-saving putts until missing a 10-footer at the penultimate hole. Oosthuizen burst onto the international stage by winning the British Open at St. Andrews 11 years ago but rather than opening the floodgates, that victory only set the stage for multiple major near-misses. It is only a month since he finished joint runner-up to Phil Mickelson at the PGA Championship. "Second again, look, it"s frustrating," he said. "It"s disappointing. "That errant tee shot on 17 just cost me, but all in all, I thought that I fought really well to stay in it and just fell short again."