In 1998 20 year old rookie Kerry Wood making his 5th major league start for the Cubs struck out 20 Houston Astros and didn't walk anyone. He gave up 1 hit. After he struck out the last batter of the game, he pumped his fist. Later he told reporters he pumped his fist because he'd been having control problems and he was psyched that he didn't walk anyone in the game. He had no idea he had struck out 20 batters and was surprised why his teammates were hugging him and slapping him on the back as if they had just won the WS.
He was the 1st NL pitcher to achieve 20 K's and was only the 2nd, along with Roger Clemens, in major league history at the time.
Many consider it the greatest game ever pitched and Wood accomplished it against a very good Astros' line-up.
The video is available on youtube.
BTW, the Cubs won the game 1-0.