Jason Giambi led Colorado’s offensive charge with a homer and four RBIs as the Rockies pounded Zack Greinke and topped the Kansas City Royals in an 11-7 slugfest on Sunday.

Troy Tulowitzki chipped in his third homer in the last four games and Ian Stewart drove in three for the Rockies, who moved back to .500 at 22-22 after grabbing the last two games of the series.

Colorado entered the contest averaging 2.6 runs per game over its past seven contests.

Greinke cruised through the first two innings before running into trouble in the third, when he allowed Giambi's three-run homer with two outs. The fourth inning turned out to be even worse, as Tulowitzki led off with a single and Greinke only managed to record one out before surrendering a two-run double to Stewart, an RBI single to Clint Barmes and an RBI single to Dexter Fowler.

Right-hander Bryan Bullington replaced Greinke and allowed an RBI single to Giambi to cap the five-run frame.

Greinke was charged with eight runs - seven earned - and nine hits in just 3 1/3 innings to fall to 1-5 and lift his ERA from 2.72 to 3.57. The defending American League Cy Young winner has now allowed eight homers this season after yielding just 11 total in 2009.

Saturday marked the first time Greinke allowed seven earned runs since getting pounded by the Chicago White Sox on July 18, 2008.

The Royals smashed out 18 hits and attempted to make a comeback, but they fell into too big of a hole too early. Billy Butler finished with four hits for Kansas City, which has lost back-to-back games for the first time since Ned Yost took over as manager on May 14.

Alberto Callaspo and Mitch Maier each added a pair of RBIs for the Royals.