The West Division races in the National and American leagues were virtually resolved yesterday, but the race in the National League East Division -- like that of its American League counterpart -- took a step the other way.

In Atlanta, the San Francisco Giants, bidding for their first playoff berth since 1971, clinched a tie for the NL West title by pounding Phil Niekro and the Braves, 15-6. Candy Maldonado had a grand slam for San Francisco. The Giants need one win, or a loss by the Cincinnati Reds, to make the playoffs. The Reds, though gasping, stayed in the race by beating Houston, 4-2. The Giants will play in San Diego tonight while the Braves are in Cincinnati.

In Minneapolis, the Twins got home runs from Kirby Puckett, Gary Gaetti and Kent Hrbek to ease past Kansas City, 8-1, and clinch a tie for the AL West. One Minnesota win or a Kansas City loss would put the Twins in the playoffs for the first time since 1970.

But as the picture cleared for the West leaders, it became a little fuzzier in the NL East. The Chicago Cubs, leading the league in home runs, increased their total with four more, including Andre Dawson's 47th, in beating the division-leading St. Louis Cardinals, 7-3, at Wrigley Field.

The New York Mets took advantage of the Cardinals' defeat, dumping the Pittsburgh Pirates, 12-3, at Shea Stadium to move 2 1/2 back. And the persistent Montreal Expos crept within three games of St. Louis by winning, 5-3, in Philadelphia. The Cardinals will finish at home with four games against the Expos and three against the Mets.

In the Giants' win, Maldonado drove in six runs to spoil Niekro's farewell game. The 48-year-old knuckleballer signed to pitch one final game for the Braves, but he wound up allowing five runs on six hits with six walks in three-plus innings and got a no-decision. He finished his career 12th on the all-time victory list with 318.

Not even a surprise eephus pitch could help Niekro, who failed to hold a 5-0 lead and left the mound with his head bowed to a four-minute standing ovation, his seventh of the day from 26,019 fans on Atlanta's final home date of the season. He made his retirement official after the game.

A two-run single by Dale Murphy and Gary Roenicke's three-run homer off Atlee Hammaker gave Niekro a 5-0 lead in the third, but the Giants got six runs in the fourth.

Robby Thompson opened with a double off the left field fence and scored on Jose Uribe's single. A walk to pinch hitter Dave Henderson and Eddie Milner's single loaded the bases.

Niekro, who escaped bases-loaded jams in the first and third innings, did not survive this time. He walked Kevin Mitchell on a 3-1 pitch, forcing home a run, and it was his final pitch.

When the game resumed, Maldonado, batting for Mike Aldrete, hit his third career grand slam and 20th home run of the season, off loser Chuck Cary (0-1).

Mitchell had an RBI single in the fifth off Rick Mahler and the Giants put it out of reach with a six-run seventh.

In the Twins' win, Gaetti, Puckett and Hrbek homered in Minnesota's five-run first inning and Bert Blyleven (15-11) pitched a five-hitter. Blyleven, pitching on three day's rest because of Joe Niekro's hip injury, struck out eight and walked two. The only run he allowed was Danny Tartabull's 32nd homer in the fourth. It was the major league-leading 45th homer allowed by Blyleven, who last year set a major league record by yielding 50.

In the Twins' first with one out, Al Newman doubled just inches from the top of the left field wall. Two pitches later, Puckett hit his 28th homer and three pitches after that, Gaetti hit a 463-foot shot for his 31st homer.

An out later, Don Baylor singled and Hrbek followed with his 34th homer, chasing Charlie Leibrandt (15-11), who threw only 19 pitches.

In Chicago, the Cubs didn't waste any time. Bob Dernier, a last-minute replacement in the starting lineup, led off the home first with a home run and later doubled and scored as as the Cardinals' magic number remained five.

Additional homers by Rafael Palmeiro, Keith Moreland (three RBI) and Dawson gave last-place Chicago a league-leading 203 homers this season. It is the first time in major league history that four teams hit 200 or more in the same year. Baltimore, Detroit and Toronto reached the mark earlier.

Les Lancaster (8-2) didn't allow a run until the sixth, but left in the next inning, having allowed three runs and eight hits. Lee Smith finished the game for his 35th save.

In New York, left-hander Bob Ojeda, a 19-game winner in the Mets' championship season last year, won his first start since coming off the disabled list on Sept. 1, and Kevin McReynolds drove in four runs.

A sellout crowd of 48,588 for the season's home finale at Shea Stadium gave the Mets a single-season record attendance of 3,027,121. New York is only the second team to draw three million, the Los Angeles Dodgers being the other. Los Angeles has topped the three-million mark on seven occasions.

Ojeda (3-5), who went on the disabled list May 9 and underwent surgery on his left elbow on May 23, gave up three runs, two earned, on six hits over six innings. Jesse Orosco pitched the last three innings for his 16th save.

McReynolds hit a three-run homer, his 29th of the season, and Darryl Strawberry had a two-run single during a six-run fourth inning when New York sent nine batters to the plate.

The Expos' kept their improbable season alive when Tim Raines hit a bloop double that was lost in the sun and scored on a wild pitch to break an eighth-inning tie with the Phillies. The Expos will begin a four-game series with the Cardinals in St. Louis Tuesday night.

The score was tied, 3-3, when Raines led off the eighth against Mike Jackson (3-9) with a routine fly to center field that Milt Thompson lost in the sun. Raines wound up at second base.

Mitch Webster then beat out a bunt single, advancing Raines to third, and Raines scored when reliever Kent Tekulve's 0-1 pitch sailed past catcher Lance Parrish to give Montreal a 4-3 lead.