Greg LeMond of the United States virtually clinched victory in the 23-day Tour de France bicycle race yesterday when he stretched his overall lead over teammate Bernard Hinault of France to 3 minutes 10 seconds.

Switzerland's Erich Maechler won the 118-mile 21st stage; LeMond was 18th. The race ends Sunday in Paris.

After the time trial, Hinault, a five-time Tour champion, promised to give up his bid for a record sixth victory and help LeMond become the first American to win the tour in its 83-year history.

In the 13th leg of the women's Tour de France, Maria Canins of Italy extended her overall lead over Jeannie Longo of France to nearly 16 minutes. FOOTBALL

All-Pro defensive end Howie Long of the Los Angeles Raiders said many of the NFL's bigger players take steroids, and he thinks the muscle-building substance should be banned.

"The public is being robbed," Long said at the Raiders' training camp. "Some of these guys are playing in a test tube. I want to know who the real guys are.

"I don't really think they the NFL want to test for it. I think they're content with giving the fans a beefed-up product.

"In the big positions, I'd say over 50 percent of players use steroids . It's just my guess. You know how many God-given 6-5, 270-pound guys there are who run a 4.7 seconds in the 40-yard dash ? Not many." . . .

Keith Byars signed a four-year contract with the Philadelphia Eagles after his agents, Richard Bennett and Brigg Owens, spent a day of negotiations with team owner Norman Braman. No terms were disclosed, but Byars reportedly will earn, with incentives, a minimum $1.6 million over the four years . . .

Former Baltimore Colts Coach Ted Marchibroda will coach the U.S. Football League's Baltimore Stars this fall pending the outcome of the USFL's anitrust lawsuit against the NFL, an unnamed source told the Baltimore Sun. JURISPRUDENCE

The jury considering the USFL's $1.69 billion antitrust suit against the NFL deliberated 7 1/2 hours without reaching a verdict. It asked to see 13 exhibits that reach the heart of the case. Deliberations resume at 9:30 a.m. today . . .

Prosecutors in Clemson, S.C., said they have reopened the investigation of two current and two former Clemson football players accused of sexually assaulting the mother of another Clemson player.

The alleged victim, a 37-year-old Walhalla, S.C., woman, initially said she was forced into a car at a gas station June 20, taken to an apartment and raped by four men. The investigation temporarily stalled when the woman changed her story, said Solicitor Joe Watson.

Charges against former Clemson players Craig Crawford and Duke Holloman initially were dropped after the complaint. The current players involved are Kenny Flowers and A.J. Johnson . . .

A Texas district judge found probable cause to send felony charges of aggravated assault against New York Mets pitcher Ron Darling and second baseman Tim Teufel to a grand jury.

The charges against Darling, 25, and Teufel, 28, could be punishable by 10 years in prison and a $5,000 fine. The players were arrested after a dispute with two off-duty uniformed policemen working as security guards at a bar last Saturday. BASKETBALL

Norm Nixon of the Los Angeles Clippers will miss the start of the 1986-87 NBA season after rupturing tendons in his left knee playing softball. Nixon is scheduled to undergo surgery Sunday in Los Angeles and will be sidelined four to six months. HORSE RACING

The Meadowlands offers a one-night harness racing record of $5,093,750 in purses tonight with a 12-race card that features five stakes races. One of them, the $1,561,500 Woodrow Wilson, will be simulcast at Freestate Raceway . . .

Mazalteca and Nothing Sweeter are prerace favorites in divisions of today's $47,600 Wistful Handicap at Pimlico. The 1 1/16-mile event for fillies and mares will be run on turf. COLLEGES

Georgetown basketball coach John Thompson said he resents the media's implication that athletics is the only facet of American society with problems.

At a Tennessee Athletics Coaches Association banquet in Nashville Thursday, Thompson said he is "sick and tired" of athletics -- and coaches -- being blamed for such societal ills as drugs.

"I think our society is in a state of over-exposure and is over-pressurized," he said. GOLF

Rookie Davis Love III shot a 5-under-par 67 for a three-stroke lead over Ed Fiori and Bobby Wadkins in the second round of the PGA's Buick Open at Grand Blanc, Mich. . . .

Nancy Scranton had an 8-under-par 64 for a one-stroke lead over Chris Johnson, the first-round leader in the LPGA's du Maurier Classic at Toronto . . .

Fred Funk of the University of Maryland won his third tournament in his last four outings, shooting 4-under-par 68 to take the Middle Atlantic PGA's Hog Neck Pro Am by one stroke over Glen Barrett of Glenn Dale and Tom Lernihan of Montclair. TENNIS

In an exhibition in Inglewood, Calif., John McEnroe played his first match since January, losing to Ivan Lendl, 6-4, 3-6, 7-6, Thursday night. McEnroe led, 4-1, in the final set. OBITUARY

Baseball Hall of Famer Ted Lyons, 85, who pitched 21 years for the Chicago White Sox, died at a nursing home in Sulpher, La. Lyons was 260-230.