Spieth, who turns 20 at the end of the month, made it into the British Open field with a five-hole playoff victory Sunday at the John Deere Classic. He became the youngest PGA Tour winner in 82 years.
“I love his game,” Mickelson said. “I love everything about it. It’s not about pretty. It’s not about making the most perfect swing. It’s about hitting shots. And that’s what he did under pressure. I love and respect that.”