Alone among major professional sports, golf relies on the players themselves to keep a tally of their score, and to sign for their totals at the end of play. Any mistake in the calculations can have dire consequences – up to and including disqualification – and yet there is no facility for a simple error to be rectified once a signature has been applied to a scorecard.

The perils of signing for an incorrect total were demonstrated by the Argentinian golfer Roberto De Vicenzo, on one of the biggest golfing stages of all – the Masters at Augusta in the US – who thereby lost the best chance he ever had of winning it. De Vicenzo, who has died aged 94, experienced his misfortune on the event’s final day in 1968. Having made a birdie at the par-four 17th to put himself in contention with the American Bob Goalby, he finished the round on 65 – seven under par – and waited for Goalby to finish. Goalby arrived with a 66, tying the two of them in first place on a four-round total of 277 and setting up a play-off for the title.

That, at least, was how it seemed. But De Vicenzo’s playing partner, Tommy Aaron, who was responsible for marking the Argentinian’s scorecard, had mistakenly recorded a four at the 17th instead of a three. He then failed to notice his error even as he added up the total at the end of the round and handed the card over for verification. Distracted by the declamatory hullabaloo of the crowd and media, De Vicenzo gave the score only a cursory glance before scrawling his signature against it.

The officials were a degree more attentive, and when the card arrived in their hands they quickly confirmed that De Vicenzo had signed for a higher total than he had actually registered. Although everyone in the golfing world knew his real score, the rules state that if you sign for a higher total, then the higher total has to stand. De Vicenzo therefore finished one shot behind Goalby, blowing his chance of a play-off and handing the American the title.

Roberto De Vicenzo teeing off on the first hole during the annual De Vicenzo Classic tournament in Buenos Aires in 2006. Photograph: Victor Grubicy/Reuters

When notified of his mistake, a crestfallen De Vicenzo famously cried out, in English: “What a stupid I am!” His anguish was justified: he was by then 45 years of age and he never came close to winning the Masters again. But his plight attracted a worldwide outpouring of sympathy and affection, heightened by his measured and sporting reaction. De Vicenzo’s name thereafter became synonymous both with sporting bad luck and with dignity in bitter defeat.

He did, however, have a highly successful career both before and after that incident. A winner of the Open Championship at Hoylake, Merseyside, the previous year – making him the first Argentinian to gain a major title – he came first in many tournaments around the world, including the Spanish, Dutch and Belgian Opens, and in several big events in the US. He won national opens in 16 countries, took nine Argentine Opens, and represented Argentina 17 times in the World Cup, leading them to victory in 1953 with Antonio Cerdá.

His 1967 Hoylake win, which he achieved by holding off strong challenges from Jack Nicklaus and Gary Player, was among the most popular in the event’s history, thanks to the elegant nature of his game, his charm and his gentlemanly behaviour.

Although he had finished in the top five at the Open nine times previously, at 44 De Vicenzo was hardly expected to win the title. He placed a bet on himself at excellent odds, and the £7,000 he took from the bookmakers was more than double his prize money. He returned to Argentina a national hero.

Born in Villa Ballester, a suburb north of Buenos Aires, Roberto was the fifth of eight children of Elias, a house painter, and Rosa (nee Baglivo), who died in childbirth when Roberto was 12. He engaged with golf at an early age by diving into the ponds on the Ferrocarril Mitre course near his home, retrieving lost balls and then selling them to supplement his family’s meagre income. He also became a caddie and, in stolen moments on the course, showed an aptitude for playing the game. Turning professional at 15, he moved on to work at the Ranelagh golf club on the southern side of the city, and won his first tournament in 1942 at the Litoral Open in Rosario, followed the next year by the more prestigious Westinghouse Grand Prix in the US – his debut international title.

A long hitter with fine control, De Vicenzo had what Golf Digest described as a “drowsy” swing that was at once rhythmic and powerful. “If you hurry,” he would say, “then nothing seems to go right.” The relaxed approach stayed with him throughout his career and served him well into his 50s, when he became a competitor in an early incarnation of the US seniors tour, winning a number of events including the inaugural US Senior Open in 1980.

BBC TV coverage of De Vicenzo’s Open victory

In the mid-1990s he stopped travelling and returned to live near the Ranelagh golf club, the clubhouse of which he made his second home. Declared one of the top five Argentinian sportsmen of the 20th century – two of the others were the footballer Diego Maradona and the racing driver Juan Manuel Fangio – he was latterly instrumental in the establishment of the Museum of Golf in Argentina, which was opened near Ranelagh in 2006 and named in his honour.

A wise and compassionate man, De Vicenzo remained sanguine about his Masters debacle, but beneath the surface the events of that final day in 1968 still rankled. At one point a group of sympathetic fellow players had a Masters green jacket specially made with De Vicenzo’s name sewn into the lining, and presented it to him as if he had been the winner. Although he was touched by the gesture he could never bring himself to wear the garment.

What he had wanted more than anything was the chance to take part in that play-off. In 2006 he reflected that “for me, the Masters hasn’t ended”, concluding: “Some day, maybe in another place, it will be decided.”

In 1955 he married Delia Puppo. She survives him along with their sons, Roberto and Eduardo.

• Roberto De Vicenzo, golfer, born 14 April 1923; died 1 June 2017