Texas' fourth consecutive victory and 11th in 14 games knocked the Blue Jays out of a share of the American League East lead, dropping them one-half behind idle Boston.
With one out in the 11th, Sierra hit his second double of the game and Pete Incaviglia was walked intentionally. Pinch-hitter Mike Stanley flied out, then Buechele singled up the middle off John Candelaria (7-4), the third Toronto pitcher.
Brad Arnsberg (5-1), the third Texas pitcher, picked up the win with 2 2/3 innings of scoreless three-hit relief.
The Blue Jays tied the score with one out in the ninth on Mookie Wilson's second home run of the season. It came off Kenny Rogers, who gave up a run in the eighth on Fred McGriff's triple and John Olerud's double.
Baltimore 5, Kansas City 1--Shortstop Cal Ripken drove in three unearned runs with a triple in Baltimore's four-run first inning as the Orioles beat Kansas City in Baltimore.
Errors by right fielder Danny Tartabull and third baseman Kevin Seitzer allowed the runners to score, giving Baltimore its 12th win in the last 18 games.
Oriole pitchers Dave Johnson (11-6), Joe Price, Curt Schilling and Gregg Olson held the Royals to six hits. Olson struck out the final two batters to get his 25th save.
Detroit 6, New York 5--Pinch-hitter Dave Bergman doubled with one out in the 14th inning and scored on Chet Lemon's triple to give the Tigers the victory at New York.
Bergman's grounder caromed off the first base bag into foul territory, where it was touched by a fan for a ground-rule double. Lemon followed with a drive to deep right-center off rookie Alan Mills (1-4), the fourth Yankee pitcher.
Clay Parker (2-1), who was traded to the Tigers by the Yankees this season, was the fifth Detroit pitcher and earned the victory with 1 2/3 innings of two-hit relief.
The Yankees overcame Lloyd Moseby's sixth-inning grand slam and a 4-1 deficit to tie the score, 5-5, in the eighth, on consecutive homers by rookie Kevin Maas, his second of the game, and Steve Balboni.
Seattle 7, Minnesota 2--Tracy Jones had two RBIs and Alvin Davis homered to lead the Mariners in Seattle.
Minnesota's Brian Harper singled in three at-bats, extended his hitting streak to 23 games, longest in the American League this season and tying Philadelphia's Lenny Dykstra for the longest in the majors.
Harper also tied Kent Hrbek for the third longest streak in the Twins' history behind Ken Landreaux's 31 games in 1980 and Lenny Green's 24 in 1961.
Seattle's Brian Holman (11-7) scattered seven hits in eight innings for his third consecutive victory.
Chicago took the second game, 4-2, as Melido Perez held Milwaukee to five hits in 7 1/3 innings. Bobby Thigpen, who leads the majors with 34 saves, saved both games with a scoreless inning.