Hosmer's three-run, two-out homer provided the edge for the Royals. He also singled twice, going 3-for-4 on the day, raising his batting average to .302, tops on the team and eighth in the league.
While the Roayls enjoyed winning for the sixth time in their last eight games, they are running out of time, both in the division and the wild card hunt.
The Tigers, despite two straight losses, are still 5 1/2 ahead of Cleveland, with the Royals seven back. Kansas City also trails Tampa Bay for the final wild card position by 3 1/2 games, though Baltimore, Cleveland and New York are closer.
Kansas City can make their own fate, as they have nine straight games upcoming against their division rivals. They have three at Cleveland starting Monday, then three at Detroit, followed by three more with the Indians at home. In this next run of games they can make or break their post-season chances.
Wacha, a reliever and spot starter, shut out the Pirates for seven innings on Sunday, allowing just two hits, as the Cardinals completed their sweep of the visitors with a 9-2 victory, reclaiming first place by 1 1/2 games over Pittsburgh.
A rookie hurler, Wacha walked two and struck out the same number, winning his third game without a loss in 12 appearances, six of them as a starter. Cardinal batters supported their mound mate with two runs in the first, three in the second and a four-run outburst in the fifth.
Having done away with Pittsburgh, the Cardinals may have to be more concerned with the Reds, winners of four straight and now tied with the Pirates for second place in the division, though the Cardinals don't face them for the remainder of the season.
St. Louis gets a day off Monday and continues their home stand with a three-game series against Milwaukee beginning Tuesday.
Today's Trivia: Starting with 2003, only two American League teams have won 100 or more games in a single season. Who are they? (answer tomorrow)
Yesterday's Answer: The Atlanta Braves won 104 games in 1993, 101 in 1997, 106 in 1998, 103 in 1999, 101 in 2002, and 101 in 2003