Jimmy Connors, whose explosive and voluble tennis is more like hard rock than the concertos for stringed instruments played by some of his colleagues, routed Tom Gullikson in the first round of the U.S. Open yesterday, then made a getaway from Flushing Meadow Park that would have made any newly affluent, groupie-chased rock star proud.

It was all there, backstage at the National Tennis Center. Screaming girls. T-shirted sidekicks to pull the star through mini-hysteria.The waiting limo to whisk him away.

During and after his impressive opening performance, witnessed by a crowd of 12,050 at the Louis Armstrong Stadium, Connors showed that he has his game face on.

Grunting fiercely, flying all over the court, attacking from the baseline with groundstrokes of fearsome pace, Connors churned through the first [WORD ILLEGIBLE] games in devastating form and thumped Gullikson, 6-0, 6-2, in just over an hour.

Then he refused, emphatically, to go to a postmatch interview. He didn't even stick around to shower and change clothes.

Moments after leaving the court, Connors and entourage made a great escape reminiscent of Fleetwood Mac - Joe Walsh's old group - dodging the fawning masses after a rousing gig.

Flanked by a quarter of his favorite "walking around guys," Connors pushed through a crowd of several hundred determined autograph seekers, mostly shrieking teen-aged girls. He did grant one interview, on the run, to Herb FitzGibbon - a former U.S. Davis Cup player who is reporting the Open for ABC Radio.

Leading the charge, armful of rackets cradled in front of his massive chest, was Doug Henderson of the Bronx, a longtime admirer of Connors who was erroneously characterized a couple of years ago as a "body guard." He preferred the title "aide de camp." Now he says simply that he is "a friend."

A former high school football player, Henderson cleared the path. On either side of Connors were two other beefy friends, one lugging a plastic ice chest. Orchestrating the charge was Lornie Kuhle of Las Vesas, Connors' globetrotting buddy, practice partner, straight man and chief "go-for," a set of roles he used to play for Bobby Riggs.

One girl burst through the protective phalanx and planted a kiss on Connors' sweaty cheek. Another pleaded for an autograph, which Connors provided without breaking stride.

The group sprinted for a gate, where a uniformed guard with a gray police sawhorse halted the madding crowd. Waiting 10 yards away, engine running, was a long, sleek Cadillac Fleetwood limousine, seemingly big enough to hold all the king's horses and all the king's men.

Kuhle opened the back door. An attractive young lady was seated expectantly inside.

"Out, sweetheart," he snarled.

She looked stunned, but complied with the order. Connors piled in, avoiding eye contact with her. Another girl was with him. Connors tore off his perspiration-soaked shirt and wrapped himself in a towel. Kuhle climbed in and locked the door.

"But I'm with Jimmy," murmured the evicted girl, plaintively. "I'm with Jimmy."

At least she thought she was.

The limo roared off, but turned after several hundred yards and stopped nearby. Kuhle jumpled out and opened the trunk. Henderson loaded the ice chest.

The obstracized girl thought she was being reclaimed on waivers. She dashed toward the back seat. Connors alighted and shrugged toward her compassionately. He motioned for her to go with Henderson. "Take care of her, O.K." he said.

Crestfallen, she scribbled a note and gave it to Henderson to deliver to Connors. He told her to call him at the Manhattan apartment where Jimmy is staying, isolated from distractions during the tournament.

What was in the ice chest?

'Steaks, Fifty-five pounds of prime beef. Jimmy is in training. He's eating good, real good," said Henderson, a sophomore majoring in history and government at Clark University in Worchester, Mass.

"Jimmy's not talking to the press this tournament. I don't know why. I guess a couple of things happened. Some things that were written have hurt him," Henderson said.

Connors has long had an adversary relationship with the press and apparently a feature story in last week's Sports Illustrated exploring his relationship with his mother and coach Gloria, infuriated him.

"That was the straw that broke the camel's back," said Henderson.

Winner of all but one of the 37 matches he had played this summer - the Wimbledon final, in which Bjorn Borg devoured him - Connors is lean and hungry. He wants desperately to regain on the hard courts of the new National Tennis Center the U.S. Open title that he won first on grass (1974), then on clay (1976) at the tournament's home for the last 54 years, the West Side Tennis Club in nearby Forest Hills.

Judging from his form against Gullikson, the left-handed and lower-ranked of the tennis twins from Onalaska, Wis., he is a good bet to reach the final and perhaps the return showdown with Borg that he so craves.

The only seeded player beaten yesterday afternoon was No. 10 Sandy Mayer, a quarterfinalist of Wimbledon this year who was gunned down by an obscure 25-year-old Canadian named Rejean Genois, late of the American Express Challengers (satellite) Circuit, 7-6, 6-2.

Genois served and volleyed well, and showed character after blowing three set points and saving one against him before winning the first tie breaker, nine points to seven. But Mayer's loss was not unexpected, because he is playing on a badly injured toe that will require surgery.

The luckiest man on the premises was 16th-seeded Arthur Ashe, who won the first U.S. Open at Forest Hills in 1968. He defeated Australian Ross Case, 4-6, 7-6, 6-1, surviving three match points in the second-set tie breaker as Case double-faulted four times and then slipped and fell on the first set point against him.

Case, who was murdering Ashe when he tried to come to the net behind second serves, led, 3-2, in the best-of-12-point tie breaker with two service points to come, but double-faulted both.

He then won three points in a row to 6-4 - match point - and served another "double." Ashe saved another match point with an ace, then pushed a backhand volley long: 6-7. He brushed aside match point No. 3 with a searing backhand down-the-line passing shot.

Case double-faulted again to fall behind, 7-8. Ashe hit a short ball, but when the 27-year-old Aussie started in to bash it, his knee buckled and he tumbled to the court on his back. Set to Ashe, and Case was finished.

"I was lucky. I thought I was gone," Ashe admitted later.

"I've never lost quite like that. I don't know what happened," said Case, who in 1974 won his biggest tournament - a $125,000 Grand Prix event in San Francisco - by beating Ashe in the final. "Whatever, I hope it never happens again."