Roscoe Tanner was reading a letter from a secret admirer today as he got in line for lunch in the players' tea room at the All England Lawn Tennis and Croquet club.

"Dearest Roscoe," he read aloud as he picked up his tray and passed by the chocolate eclairs and cream cakes. "Hmmm, my wife wouldn't like this too much."

By the time he got to his main fare steak, extra french fries, hold the boiled tomatoes -- he was laughing hysterically, and blushing slightly.

"Is it the kind that Borg gets all the time?" asked Dennis Ralston, who coaches Tanner and several other American players.

"I don't know. It could be be a real snorter," said Tanner. "It's working up to it pretty well."

By the time he picked up his Coca cola, fruit salad and two packs of chewing gum, he had read some more aloud:

"There are two men in my life, Roscoe -- you and my boyfriend Charlie. When I watched you on the television the other day, I got so excited I forgot my boyfriend was there. I was flushed, and Charlie stormed out. He said quite seriously, 'I never want to see you again. I don't know what you see in that man Tanner.'"

"I don't know, but imagine me breaking up a happy relationship just by playing tennis," said Tanner, trying unsuccessfully to sound serious.

Bjorn Borg, the erstwhile "teen angel" of tennis who started the teenybopper craze at Wimbledon in 1973, regularly gets such frivolous mail. After all, he is still only 23, unwed [though long engaged to Romanian player Mariana Simionescu], and is seeking his fourth consecutive singles title at Wimbledon.

But Leonard Roscoe Tanner III, the clean-cut and happily married favorite son of Lookout Mountain, Tenn.? Even with his new-look permanent, he isn't the type the groupies swarm.

"I don't get many letters like this. That's why it's so funny," grinned Tanner, folding the admiring missive -- on shocking yellow paper, no less -- and putting it in his purse.

Indeed, Tanner is the forgotten man of this year's Wimbledon, Charlie's Angel notwithstanding. But he may not be for long. With John McEnroe's Angel notwithstanding. But he may not be for long. With John McEnroe's premature departure at the hands of Tim Gullikson on Saturday, Tanner became the clear favorite to reach the final in the bottom half of the draw.

A semifinalist here twice before and the No. 5 seed this year, Tanner is one of only three of the top men who made it through the first-week binge of upsets to his appointed place in the quarterfinals.

But he did so with such a low profile that not many people have noticed how well he's playing. Tanner has lost one set in beating fellow American left-hander Van Winitsky, Australians Peter McNamara and Ross Case, and seeded Argentinian Jose Clerc, but he has played his matches in compartative privacy. Three of the four have been "out in the country," on courts 4, 5 and 6.

Most people at Wimbledon characterize Tanner simply as an electrifying server. They associate him with one match: the 1976 quarterfinal in which he obliterated Connors with what one old hand described as "the most impressive display of serving seen on the Center Court since Ellsworth Vines in 1932."

They don't realize that Tanner is a more complete player now who has worked with Ralston intensively to improve his ground strokes, his movement both in the backcourt and at the net, and his attitude on the court.

With McEnroe out, Tanner is a good bet to reach the final in a half of the draw he shares with Adriano Panatta, Pat DuPre and Gullikson. Panatta plays DuPre and Tanner plays Gullikson, who has a 2-0 record against him but has never played on Wimbledon's Center Court, in the quarterfinal matches Tuesday.

Nearly everyone assumes that the real "final" will be played Thursday, between Connors and Borg, who have been in the title match the past two years. Borg is expected to bury Tom Okker, as he did in last year's semifinals, and Connors to rout former NCAA champion Billy Scanlon in Tuesday's other quarterfinals.

Then whoever wins the Borg-Connors semifinal will coast to the championship in an anticlimactic final Saturday afternoon. At least that is the prevailing logic, especially among bookies who have made Borg a 4-5 favorite and Connors 2-1.

But Tanner, fit and confident, is having none of that. "At this state, anything can happen -- especially on a grass court," he says. "Everybody was asking me how I planned to play McEnroe in the quarters, but that's not too important now, is it?"