In the first game of his first Wimbledon match Monday, Jimmy Connors was stunned to hear the umpire say, "Mr. Connors, could you hold down your grunting, please." At first, Connors laughed. Then he realized he old fellow in the blazer and coat of arms was serious.

"Default me," snapped Connors. "I couldn't stop grunting if I wanted to. That's me."

At the age of 28, after 16 years of serious tennis, Connors is still the best grunt in his sport. For him, the game isn't finesse or strategy, nor is it the simplicity of serve and volley power. Connors' game is trench warfare, just as it is when he was the world's No. 1 player five times during the '70s.

That seems to have been forgotten here. Connors is the overlooked superstar of this Wimbledon. Seldom has a men's No. 3 seed seemed so far from the public mind. Call one of London's legal bookies this morning and here were the shocking odds on the favorites: Bjorn Borg, even money; John McEnroe, 5 to 4; Jimmy Connors, 10 to 1.

Jimmy Connors 10 to 1? No way, not yet. Ask him. "When I walk in a place, I'm not considered No. 3. I'm considered who I am," said Connors after completing his second-round victory today over Chris Lewis, 7-6, 7-6, 6-3. "As far as playing in the shadow of anybody, I never have and I never will, 'cause I've created my own image and I'll play off that forever.

"As far as those guys go," said Connors, meaning Borg and McEnroe, "they-play their time, I play my time and eventually we'll play each other. I'll be there. That's the way you find out."

That is Connors at his defiant, brash best. But it's far from the whole truth and nothing but the truth. Connors may be holding on with style and panache, but he is holding on by his fingernails, nontheless.

Connors has never needed power tennis more than he does now. The reason Connors is the best of the rest in men's tennis behind the big two is simply that he wants it more.

"Borg and McEnroe are the only two guys out here who are feared anymore," said Arthur Ashe, U.S. Davis Cup captain. "Everybody else is fair game, including Jimbo."

In retrospect, the most remarkable feature of Connors' career may be the spectacular mileage he has gotten out of a game made up of so many fair to middling components. His serve has never been intimidating, so he has never been able to get to the net enough to be a really potent volleyer. The whole tennis world knows that Connors' forehand approach is abysmal; it seems he has hit the cord a million times with that shot which he has continued, with typical defiance, to blast with topspin.

Connors comes here with the same weapons as always, tactics he has not altered since his mother ingrained them in him -- baseline shots from either wing and that trademark ability to return serve violently, even while the ball is on the rise.

though he has only won Wimbledon once -- in his peak year of 1974 -- Connors has been in a blissfully upbeat mood all week. "Things have to go right, fall in place, for you to win Wimbledon," he says. And they are going right, so far.

"I'm serving better and better now. For years, I thought that you had to pound the serve even harder on grass because it was such a vital part of the game on this surface. I was always going for that little extra," said Connors. "Now, I realize that's backwards. You don't have to work it as much. Let that slick grass do your work for you. I'm letting it help me this year . . . finally."

Also, since his marriage and the birth of his son, Brett, who will be 2 years old in July, Connors has gradually trimmed his tournament schedule and, consequently, revived his lagging appetite for competition.

"The last couple of years, I might have come here stale," he said today. "But in the last year, I've reversed that. I was wishing for this thing to start six days ahead of time. I'm so eager to play that I said to myself, 'When did I last feel like this?'"

For Connors, the spirit of the game is essential. He cannot play well unless he is at fever pitch.

Unfortunately for him, that does not mean hay fever.

Connors and pollen are natural enemies and few places on earth are more legendary for causing sneezes than Wimbledon. "For 16 years, I've tried to find a medicine strong enough to beat my allergies, but weak enough so that it didn't make me dopey or kill my edge," said Connors. "The worst place of all is here."

Many things are in Connors' favor here, including his strong play of late. However, the one of the favorites he does better against -- McEnroe -- is in the other half of the draw, while the one man on earth who truly bamboozles him consistently -- Borg -- appears to have a cakewalk into a semifinal showdown with Connors.

"I'm not worrying about anything. They say they're trying to crack down on grunters here this year. Well, I can't worry about that. I invented the grunt. And I can't be concerned that Borg always plays inside (on the Centre and No. 1 courts) like today. I'm not the schedule maker.

"The only thing that really bothers me here is when it's on-and-off all day because of rain. You not only stiffen up physically, but you have to reach that mental pitch again. I live in this body day after day, so I know its limitations -- how to work around 'em or just live with 'em. You can only get up so many times."

For Connors, that side of the game is, perhaps, more disproportionately important than for any other player of his time. The gift that Connors brought to tennis is not a technical or tactical one; it was a quality of supreme combativeness.

And although he is only No. 3 and hanging on, although the smart money bookmakers says he's a 10-to-1 longshot now, Connors has not lost his fire.

"I can't say how many shots I've got left at Wimbledon," said Connors. "But I'm not going to cheat myself out of any."