CINCINNATI -- There is a long list of disputes, gamesmanship and skirmishes -- big and small -- that have dotted the rivalry of the Reds and Cardinals over the years. For the second time this season, Reds right fielder Nick Castellanos became part of a page in that history.

The tone of the 12-2 Reds rout over the Cardinals in Game 2 of their seven-inning doubleheader on Wednesday -- after they fell, 5-4, in Game 1 -- was established early when Castellanos slugged two home runs with six RBIs through two at-bats in the first two innings. But it was the grand slam Castellanos hit in the bottom of the second that drew dispute from the St. Louis dugout.

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“My view is that was my second homer and I drove in six," Castellanos said. "All of a sudden, there was an issue. There was no issue when [Jon] Lester absolutely carved me up. And there was no issue in the first game. But then there was an issue.”

Facing J.A. Happ for the second time, Castellanos crushed a 1-2 pitch to left-center field for a grand slam and a 6-1 lead. Upon returning to the dugout, Cardinals manager Mike Shildt requested that umpires check Castellanos’ bat, which had been given to a kid seated by the home dugout.

“Bat was chipped. It’s just by rule," Shildt said. "Look, I don’t want to make it a big deal. The guy hit a homer with the chipped bat, so good for him. Put two good swings on it. Really wasn’t going to say anything initially, but the bat was ran out of there so quickly. I didn’t want the bat to get gone. I knew there really wasn’t any recourse."

The four umpires convened and then approached the Reds' dugout to discuss with Castellanos and manager David Bell and request the bat be inspected, because Shildt thought it was chipped at the end of the barrel. The bat, which was retrieved, was looked over and given back to Castellanos before being returned to the young fan.

"[Shildt] is trying to do anything that he can to make his team have the best chance to win, right? The second game was making them check a bat that drove in six runs that put them ahead," Castellanos said. "I decided to give that dangerous piece of lumber to some lucky kid that was sitting above the dugout, so at the end of the day, everybody wins.”

Crew chief Phil Cuzzi determined that nothing on the bat affected the outcome of the contact. 

"It was brought, obviously, to our attention that the cupped portion of Castellanos’ bat was broken off, which when we inspected it, it was," Cuzzi said. "We simply told him, 'We’re not going to take away the home run. You just can’t use the bat.' It was as simple as that."

Then Shildt requested a video review for a rules check to confirm that the umpires followed the correct procedures under MLB rules 3.02 and 6.03 (a)(5).

Rule 3.02 states "The bat shall be a smooth, round stick not more than 2.61 inches in diameter at the thickest part and not more than 42 inches in length. The bat shall be one piece of solid wood."

Specifically, in 6.03(a)(5), “A batter shall be deemed to have used or attempted to use an illegal bat if he brings such a bat into the batter’s box" -- and the batter can be called out.

Said Castellanos: "The home-plate umpire from the first game [John Trumpane] -- actually in my last at-bat -- told me, he’s like, ‘Hey Nick, you see your bat at the top?’ I said, ‘Yeah, yeah, it’s fine.’ He goes, ‘OK,’ so the umpire in the first game was aware that my bat was in that condition.”

It was determined that the umpires could use their own discretion to allow the home run ruling to remain. But Castellanos' bat was removed from further use for safety reasons. 

"It didn’t give him any advantage," Cuzzi said. "It’s really just more of a dangerous thing because it’s easier for that bat, if he gets a ball off the end of the bat, it could shatter and who knows? It goes in somebody’s eyes, in somebody’s face. It was more of a safety thing, but it had nothing to do with the home run. The home run was never in question about not counting it."

Therefore, the grand slam counted, giving Castellanos his 26th homer of the season, one shy of his career high.

"I thought the crew handled it well," Shildt noted.

Castellanos noted he's been using the bat since it was initially damaged during his final at-bat on Sunday at Miami. 

"I’ve been doing it all year because I don’t want to just waste a bat," Castellanos said. "I will just pick the pieces of wood that are pushed back until the entire bat is intact. Then I just go and use it. Actually my Opening Day homer against them had a chunk missing because the same thing happened in Spring Training.”

Batting in the bottom of the first inning against Happ, Castellanos drove an 0-1 pitch into the left-field seats for a two-run homer to give Cincinnati a 2-1 lead. 

"Both of those home runs were big, that got us going in the right direction right from the beginning of the game," Bell said. "Sometimes that’s a little bit more important than others. Tonight was one of those games."

Three batters after Castellanos' slam, Kyle Farmer added a two-run homer against reliever Junior Fernández to make it an 8-1 game. It boosted the fortunes of Reds starting pitcher Sonny Gray, who began the 12-batter rally with a single and pitched five innings for the victory. Gray allowed two runs and two hits on a pair of solo homers -- including Tommy Edman's to open the evening -- with three strikeouts.

By snapping a four-game losing streak and salvaging the final game of the three-game series with the Cardinals, the Reds moved back to a half-game ahead of the Padres for the second National League Wild Card spot. The Cardinals and Phillies are 2 1/2 games behind Cincinnati. 

Castellanos is batting .392 with five homers and 12 RBIs this season vs. St. Louis. He slugged a homer against them on Opening Day and was hit by a pitch in the season's second game. Later the same day -- April 3 -- he flexed over pitcher Jake Woodford after scoring on a wild pitch to spark a benches-clearing scuffle. The incident resulted in a two-game suspension for Castellanos. 

"It gives me an extra edge," Castellanos said of playing the Cardinals. "I’m naturally a happy person but then for the moments I am pissed for whatever reason, it’s amazing how I am able to lock it in. Riddle me that.”