Beforehand, he shrugged off all the intangibles that seemingly would have had him listed among the favorites to take home Monday's Derby trophy.
You know, the fact that he's a left-handed pull hitter taking swings in a left-handed friendly Yankee Stadium. Oh, and not to mention his American League-leading 23 home runs. Apparently that didn't mean much, either.
As it turns out, Sizemore performed admirably enough, but fell just short of advancing to the second round of the Home Run Derby with his total of six first-round homers. And while not the most verbose of players on the AL squad, Sizemore's grin afterward spoke as powerfully as his words.
"It was a little nerve-wracking up until the point that it started," he said. "But once I did, I had a good time and relaxed and tried to enjoy it."
Sizemore was the first of four American League representatives to take a swing at clearing the Yankee Stadium fences. He followed Florida's Dan Uggla, who set the starting standard at six home runs.
Halfway through the eight-player first round, Sizemore looked to be in good position to be one of the four players to advance to the second round of the three-round event. He and Uggla stood atop the leaderboard until Houston's Lance Berkman went deep eight times to become the front-runner.
Minnesota's Justin Morneau followed with his own eight-homer performance before Milwaukee's Ryan Braun overcame an 0-for-6 start to finish with seven. Texas' Josh Hamilton then sealed the final spot in the second round with a record-setting first-round performance. His 28-homer barrage, which broke Bobby Abreu's single-round mark of 24 in 2005, included at least three 500-foot-plus shots.
Now that got Sizemore talking. Hamilton's performance was the only thing Sizemore didn't downplay on the night.
"He didn't do that in a season," Sizemore said. "He did that in a round. He was even mis-hitting balls and they were going out of the park. He's a freak of nature."
Hamilton would end up cruising into the final round, but he was edged out by Morneau for the eventual title.
As one of five hitters swinging from the left side of the plate, Sizemore came in with a distinct advantage considering the Yankees' short right-field porch. And though he came into the Derby intent on not changing his swing, Sizemore admitted afterward that he wasn't in fact taking his normal batting practice cuts.
"This competition, it changed a little, maybe a little more to try and get the ball in the air," he said. "I was just trying to hit it out."
With Indians bench coach Jeff Datz pitching sidearm to him, Sizemore took the first two pitches before connecting on the third and going yard into the right-center-field seats.
"You always want to get the first one out of the way," Sizemore said afterward, confessing that the nerves attached to participating in his first Home Run Derby didn't really dissipate until after he homered.
Then the show started. His next four home runs all landed in the right-field upper deck, including a 448-foot blast that gave him home run No. 5. It was also enough to get a "Wow" out of Boston's David Ortiz, who has been known to hit some deep drives himself.
The 25-year-old Sizemore then tied Uggla's total with a homer that landed in the Yankees' bullpen. He had two more shots at surpassing the Florida second baseman, but fell short on both.
Sizemore's natural tendency to pull balls actually may have cost him the chance at tacking a few more onto that total. Six of his 10 outs were foul balls that landed in the seats along the right-field line. That included three that were of home run distance.
Despite the inability to advance past the first round, Sizemore left Yankee Stadium on Monday night glad to have competed in the record-setting event -- enough that he said he'd be willing to take part again.
"I would definitely consider it," he said. "I definitely wouldn't be opposed to doing it again."
Jenifer Langosch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.