A roundup of the week Aug. 27-Sept. 2

BOXING—PINKLON THOMAS scored a 12-round majority decision over Tim Witherspoon to win the WBC heavyweight title (page 54).

CYCLING—REBECCA TWIGG of Seattle beat France's Jeannie Longo to win the 3,000-meter pursuit title at the world championships in Barcelona, with a time of 3:45.02.

PRO FOOTBALL—NFL: With auditions and previews finally over, the Sunday matinees opened with some surprising performances by a number of understudies. Kansas City's quarterback Todd Blackledge stepped in for the injured Bill Kenney and, in his first pro start, passed for one TD and ran for another as the Chiefs upset the Steelers 37-27 (page 44). Another quarterback making his first pro start, six-year veteran backup Pat Ryan, threw for two TDs in the Jets' 23-14 defeat of the fumbling Colts in the first NFL regular-season game in Indianapolis. With William Andrews lost for the season with a wrecked knee, Gerald Riggs took over and carried 35 times for 202 yards and two TDs as Atlanta upended New Orleans 36-28. In Denver, Gary Kubiak replaced the injured John Elway (bruised left shoulder) and mounted a 75-yard fourth quarter drive that gave the Broncos a 20-17 victory over Cincinnati. The perennially injured Phil Simms brought back memories of Y.A. Tittle with the second-greatest passing day in Giant history, completing 23 of 30 for 409 yards and four TDs in a 28-27 win over Philadelphia. Of course, some old stars were also on display. The second-year tandem of Dan Marino and Mark Duper again provided visions of Griese-to-Warfield, Marino hitting his favorite receiver for first-half TDs of 26 and 74 yards en route to a 311-yard, five-TD performance in the Dolphins' 35-17 rout of Washington (page 14). San Francisco got two TD runs from Wendell Tyler and three field goals from Ray Wersching, including the game-winner from 22 yards with :04 left, to beat Detroit 30-27. A healthy Dan Fouts led San Diego past Minnesota, 42-13. Fouts completed 21 of 28, including three to Charlie Joiner for 52 yards as the 15-year veteran receiver became the fourth member of the NFL's 10,000-yard club. The Patriots' Steve Grogan hit Stephan Starring for a 65-yard TD on the game's second play in a 21-17 defeat of Buffalo. Green Bay tripped up St. Louis 24-23, and the L.A. Raiders launched their title defense by beating Houston 24-14. Tampa Bay continued its cruise to nowhere, losing to Chicago 34-14.

GOLF—SCOTT VERPLANK beat Sam Randolph 4 and 3 to win the U.S. Amateur championship in Edmond, Okla. (page 48).

Wayne Levi shot a nine-under-par 275 to win a $300,000 PGA event in Endicott, N.Y. by one stroke over Hal Sutton.

HARNESS RACING—BALTIC SPEED, Jan Nordin driving, took the winner's share of $300,975 in the $601,950 World Trotting Derby in DuQuoin, Ill. The 3-year-old colt won two of three heats, trotting the final mile in 1:56[2/5] to beat Ambro Crouch by 2½ lengths.

HORSE RACING—MISS OCEANA ($5.60), Eddie Maple up, beat Sintra by two lengths to win the $111,400 Gazelle Handicap at Belmont Park. The 3-year-old filly ran the 1‚⅛ miles in 1:47[3/5]

Fashionably Late ($9.40), Chris McCarron up, covered the 1‚⅛-mile turf course at Del Mar in 1:49[2/5] to win the $160,150 Del Mar Oaks. The 3-year-old filly beat Lucky Lucky Lucky by a head.

MOTOR SPORTS—MARIO ANDRETTI, in a Lola T-800, finished 37.9 seconds ahead of Bobby Rahal, in a March, to collect the $46,970 winner's check in a 200-mile CART event in Lexington, Ohio. He averaged 100.888 mph over a 15-turn circuit.

SOCCER—NASL: The league's playoff picture became muddled when only one of the top four teams could win a game. In the Western Division, first-place Vancouver lost 2-1 in New York, and second-place Minnesota lost 2-1 to Golden Bay. San Diego thus jumped into the race with two shutouts, 4-0 over Chicago and 6-0 over Tulsa, moving the Sockers into a tie with Toronto and New York for the final wild-card spot. The Cosmos' win over the White-caps, coupled with the Blizzard's 5-0 loss to Tulsa, produced a first-place tie in the East.

TRACK & FIELD—JOHNNY GRAY set an American record of 1:42.96 in the 800 meters in Coblenz, West Germany, lowering by .32 of a second the mark he established in Zurich on Aug. 22.

Sergei Bubka of the U.S.S.R. lost his world pole vault record momentarily to France's THIERRY VIGNERON in Rome, but regained it by clearing 19'5¾", an inch higher than Vigneron and 1½ inches better than the mark he set in July in London.

MILEPOSTS—ANNOUNCED: By the MISL, the acceptance of four NASL teams—New York, Chicago, San Diego and Minnesota—for the 1984-85 indoor season. Each team will pay a $400,000 entrance fee over four years and retain the right to play outdoors in the off-season. The Tulsa Roughnecks, defending champions of the NASL, were rejected by the MISL and will fold at season's end.

DISQUALIFIED: From the 1984 world motor racing championships, the Grand Prix team of England's KEN TYRRELL, 60, for fuel and weight violations.

FIRED: By the Montreal Expos, manager BILL VIRDON, 53, who had a 146-147 record since taking over the club in 1983. He was replaced by his predecessor, JIM FANNING, 56, who is the team's personnel director. And by the Seattle Mariners, manager DEL CRANDALL, 54, who had a 93-131 record since he took over for Rene Lachemann on June 25, 1983. His replacement is coach CHUCK COTTIER, 48.

RESIGNED: CHARLEY PELL, 43, as head football coach of the University of Florida, effective at the end of the '84 season.

TRADED: By the Houston Astros, infielder RAY KNIGHT, 31, to the New York Mets for three minor-leaguers.