After using their petrodollars to buy conglomerates, hotels and famous paintings, Arab moneymen now have turned to the world of sport and launched an ambitious, free-spending campaign to buy some of the world's top soccer talent from Brazil.

The first to go was superstar Roberto Rivelino, who last week signed a two-year, multimillion-dollar contract with the Al Hilal club of Saudi Arabia. A member of the Brazilian national team that won the World Cup in 1970 and captain of this year's cup team, Rivelino has been Brazil's biggest soccer idol since Pele.

As Rivelino tells it, the Saudis hope their country, with a population of less than 9 million, little grass and few playing fields for the world's most popular sport, will be swept by the kind of soccer boom that struck the United States after Pele signed with the New York Cosmos. Rivelino's contract calls for him to aid this effort with soccer camps and personal appearances throughout the Arab world.

Al Hilal's interest in the 32-year-old Brazilian, who had been talking of retirement, began when the Brazilian national team made a side trip to Saudi Arabia during a European tour earlier this year. Negotiations started in earnest after the cup, and late last month Rivelino and his wife were invited to Riyadh to work out the final arrangements for the contract.

By all accounts, Rivelino's reception in Saudi Arabia was worthy of a head of state. After a long flight on a Concorde from Rio, he was greeted at the airport by thousands of fans waving flags, whisked away in a RollsRoyce to one of the most luxurious of the royal residences and honored with a lavish multicourse banquet attended by members of the Saudi royal family.

The deal finally agreed upon, which the Brazilian press has dubbed "Rivelino's thousand and one Arabian nights," comes with some unusual fringe benefits. In addition to receiving a new Mercedes Benz and a reported $10,000-a-month living allowance, Rivelino will be housed in one of the spare palaces of Prince Khaled Al Saud, nephew of Saudi King Khaled and owner of the Al Hilal team.

But the Saudis also have let it be known that they do not intend to settle for just one Brazilian star. Using the same combination of petrodollars and extravagant hospitality that won over Rivelino, they now are wooing a half-dozen of the other better players here in hopes of fielding a full battalion of Brazilians when the Saudi soccer season begins next month.

To the alarm of Brazilian fans, the Saudis have focused their attention on one of the most flamboyant players on the nation's most popular team: 26-year-old Artur Antunes Coimbra of the Flamingo club, who plays under the name "Zico". Negotiations got under way here last week and the Arabs' initial offer was a whopping $2.5 million, with an equal amount to go to his team.

The negotiations are being conducted by Joao Saad, a Brazilian of Lebanese descent who has been appointed by Prince Khaled and Prince Fahd ibn Abdul Aziz, another soccer-crazy member of the Saudi royal family, as their agent here. Saad says the princes have authorized him to make "extensive investments" in Brazilian soccer players.

"The princes are interested in players, the best Brazil has to offer," said Saad. "But they're also after trainers, coaches, administrators and anybody else that can help improve the quality of soccer played in the Arab world.

Brazilian soccer experts attribute the sudden surge of Saudi interest in the sport to nationalistic pride brought about by the country's poor showing in international competition. The only mideast nation to reach June's World Cup tournament was oil-producing rival Iran, which earned its place by narrowly defeating tiny Kuwait - a country whose soccer fortunes have soared since hiring a Brazilian coach for its team.

Saad has hinted that his next move will be to counteract the Kuwait strategy by offering a million dollars-plus deal to Claudio Coutinho, coach of the team that represented Brazil at this year's World Cup.