"I told him I'd give him all the money in my wallet if he got my 100th RBI," Bryant said, laughing. "I owe him some money."
Bryant connected on a 3-2 fastball from the Pirates' Steven Brault with one out and one on in the sixth, launching the ball into the left-field seats at PNC Park.
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A leading candidate for the Most Valuable Player Award, Bryant began the day leading the NL in runs scored with 121, and he's second in home runs behind the Rockies' Nolan Arenado. Bryant's 39 homers are the most by a Cubs player since Derrek Lee hit 46 in 2005.
Bryant was motivated this season to not finish at 99.
"Thinking back to last year, ending on 99, I didn't want to do that two years in a row," Bryant said. "I reminded myself I'm a completely different player from last year. I knew it would happen. You want it right away, and sometimes it doesn't come to you right away and you start trying harder, and then it happens out of the blue. I'm very happy it's over. We don't need to talk about it anymore."
Bryant was able to forget about last season once the Cubs began postseason play.
"In this situation, if I didn't get it this year, it's not the end of the world," Bryant said. "I'm living a dream."
What's next? Well, 40 is a nice number as far as home runs go.
"That's the next thing," Bryant said. "It never ends."
Carrie Muskat has covered the Cubs since 1987, and for MLB.com since 2001. She writes a blog, Muskat Ramblings. You can follow her on Twitter @CarrieMuskat and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.