Baseball fans have long been warned to look out for foul balls and flying bats.
Now add falling letters to the list.
The middle-aged man had a scrape after a foul ball by home run leader Jose Bautista of the Blue Jays dislodged one of the letters in a tribute honoring Robinson's retired No. 42.
The letter fell about 30 feet from the facing over the third deck behind home plate in the seventh inning of the Texas-Toronto game.
"I was very surprised, because I didn't expect a 'B' to fall on me," said the injured fan, who gave only his first name as Ian and said he was a season-ticket holder from Toronto. He was watching the game with his son.
Although he was sore, the fan who was struck said the injury wouldn't prove too serious; he throws left-handed.
The white letter, some two feet high, bounced down the aisle and was picked up in the front row by fan Bruno DeRose, who proudly held it over his head. Other fans booed when stadium security took the letter away.
"They should have at least given me a couple of tickets or a ball," DeRose said. "I couldn't believe it happened."