The rocketing serves of Australian tennis veterans Tony Roche and John Alexander swept Australia to a commanding 2-0 lead over Italy in the Davis Cup final today.

The 32-year-old Roche, who has said goodbye to tennis more often than Frank Sinatra has quit show business, whipped Italy's top player, Adriano Panatta, in straight and swift sets, 6-3, 6-4, 6-4.

It was the match Australia wanted most to win to set it on its way toward its first Davis Cup victory on Australian soil in 10 years.

Alexander beat Corrado Barazzutti, 6-2, 8-6, 4-6, 6-2.

Trouble in recent years with leg and back injuries, Roche was a doubtful starter until just before the match. For the past week, he has been under constant treatment by a masseur for a muscle injury in his back.

But the veteran of Australia's tennis glory of the '60s was playing at Sydney's White CIty court, always his favorite, Roche showed Panatta why. The strong, tricky winds suited Roche's powerful lefthanded serve and volleying.

Alexander has ofter looked like he would join the list of legendary Australians led by Rod Laver, John Newcombe and Ken Rosewall, but has never quite managed it.

But few observers before the match thought he would have trouble with Barazzutti, whose total experience on grass courts amounted to practice sessions in Sydney the past month.

Alexander cruised throuhg the first set but had to battle to win the second.

With mass migration since World War II, Sydney has become one of the most Italian cities in the world outside the home country. And half the 5,000 spectators at White City roared their support for Barazzutti as he threw himself after every point in the third set. He held on to win, 6-4.

But Alexander came back strong after a 15-minute break in the 90-degree Sydney heat. He served, smashed and volleyed his way swiftly through the fourth set.

It was a grim day for the Italians, who won the Davis Cup last year by beating Chile in the final, having thrashed Australia - on clay in Rome - 4-1 in the semi-final.

There was element of nostalgia before the best-of-five-match series began. The opposing captains - Neale Fraser for Australia and Italy's Nicola Pietrangeli are old playing rivals from the 1950s.

They both played for their countries on the only previous occasions Italy met Australia in a Davis Cup final. In 1960, Australia thrashed Italy, 4-1, and the following year routed the Italians, 5-0. The only match Italy has won was the 1960 fifth singles victory by Pietrangeli over Fraser.

Off today's performances, Fraser's final revenge for that faraway stain on his great career looks certain. In the unlikely event of Australia losing tomorrow's doubles, Roche is odds on to win his second singles the following day and clinch the cup.