The Orioles won for the seventh time in eight chances with Showalter at the helm in Tuesday's opener of this set, with Luke Scott and Felix Pie each hit three-run homers to help Baltimore to a 14-8 rout.
Scott also doubled, knocked in four runs and scored twice, while Matt Wieters clubbed a two-run homer and drove in three runs for the Orioles. Corey Patterson added a solo home run in the win.
The 14 runs were the most Baltimore had scored since crossing the plate 16 times against the Angels on Aug. 14 of last year. The Orioles also collected 13 hits and raised their average under Showalter to .300 - 44 points higher than before his arrival.
The beneficiary of the offensive onslaught was Jake Arrieta (4-3), who struggled through six innings but was able to get the victory after allowing six runs -- five earned -- on six hits.
Michael Brantley had a two-run homer, finished with three RBI and scored three times for the Indians, who have dropped three straight and five of seven. Shin Soo-Choo had a two-run double in defeat.
Justin Masterson (4-11), who was coming off a win over Boston on Wednesday by limiting his former club to a run and four hits in five innings, wasn't as fortunate in this one. The big right-hander lasted five frames and surrendered seven runs -- four earned -- on six hits, while walking three and striking out three in taking the loss.
Heading to the hill for the O's tonight will be right-hander Brad Bergesen, who is 3-9 and hasn't won since beating Seattle back on May 12. Bergesen did not get a decision on Friday against Chicago but pitched well, surrendering one run and five hits in seven innings. He had given up two runs in seven innings in his previous outing, but is still pitching to a 6.26 ERA on the year.
Cleveland, meanwhile, will counter with 25-year-old righty Josh Tomlin, who absorbed the loss his last time out. After giving up two runs through his first two starts, Tomlin was hit by Boston for four runs and four hits in seven innings on Thursday, dropping him to 1-1 to go along with a 2.79 ERA.
Both starters will be facing their opponents for the first time tonight.
Cleveland took two of three from Baltimore earlier in the season. A win tonight would also give the Orioles their first series win in Cleveland since taking two of three during July of 2006.