John Lloyd is not a braggart, but he knows his tennis game well enough not to sell himself short at the US Open Championships in New York. ''All I can say is that it will take a good player to beat me,'' he says.
He meets just such a player in today's quarterfinal action, when he confronts Jimmy Connors, the two-time defending champion. Ordinarly a match between the tournament's reigning shotmaker and a relative journeyman like Lloyd would be pretty humdrum stuff. This one has built-in interest, though.
First, it pits Chris Evert Lloyd's husband, John, against Chris's old boyfriend and ex-fiance. The tennis triangle won't really have any bearing on the match, since Lloyd and Connors were never rival suitors, but it does make an unusual backdrop.
Second, it brings together two crowd favorites on either end of the competitive spectrum. American fans admire Connors for the grit and determination he's displayed in staying at the top of his profession. They also have taken a liking to the handsome Lloyd, a courteous Englishman who has shown his character in battling back from a low ranking (he has gone from 387th to 49 th in the world) and some strains on his marriage. ''It's like Wimbledon for me here; it's just incredible,'' John has said of the enthusiastic receptions at the National Tennis Center.
Americans, of course, love an underdog, a role that Lloyd clearly assumes in this drama. He has never taken a set off Connors, yet is playing his best tennis ever. To reach the quarterfinals, a feat no British male had accomplished at the Open since 1966, John beat Peter Fleming, Libor Pimek, 12th-seeded Johan Kriek, and ninth-seeded Henrik Sundstrom.
The height of Lloyd's career came in 1977, when he was the runner-up at the Australian Open and rose to No. 23 in the world rankings. After marrying in 1979, his commitment to tennis waned and his rating plummeted dramatically. He won a mixed doubles crown at Wimbledon with Wendy Turnbull in 1983, but confidence in his singles play didn't begin to return until he reached the final 16 at last year's US Open. Down side of football
Pro football has increasingly become a war of attrition. Just last weekend a handful of key players were sidelined, and the 16-game season had only begun. Among those injured were Seattle running back Curt Warner, Denver quarterback John Elway, Dallas wide receiver Tony Hill, and Pittsburgh quarterback David Woodley. Warner's season was likely ended by a knee injury, which is what terminated William Andrews's 1984 campaign during the pre-season. Andrews was an all-pro running back for the Atlanta Falcons last year and Warner the heart of the Seahawk offense as only a rookie.
The disturbing number of fallen players is hardly limited to pro football either. The college game sees its share too, a problem that Iowa Coach Hayden Fry blames on equipment that ''has not kept up with the speed and the impact of the game'' and on weight-training programs that have increased player strength across the board. Touching other bases
* There are lots of handsome sports books on the market, but maybe only one that belongs in a display case. The volume is ''The Challenge 1983,'' a limited edition chronicle of last year's America's Cup yachting competition that sells for $1,000. The book, published by Australian Robert Gunn, tells how Australia II wrested the cup away from the US in the first successful challenge in 132 years. Each of 1,000 rawhide-bound and numbered copies comes with a timber case. And with 480 editions unsold, you could still be the first on your block to own one.
* Today's ever-bigger basketball players make for increased congestion on the court. If they ever outgrow the present playing surface, an alternative to increasing its size would be to decrease the number of players per team from five to four. In the United States, however, the first step to decongesting things around the basket would be adoption of the larger, fan-shaped, three-second lane used in the Olympics.
* The 1936 Berlin Olympics, in which Jesse Owens undermined racist Nazi notions, were the first to be televised. Viewing was limited to 25 sets at theaters throughout the city.