Last year, the Dutchman completed an unprecedented double, winning both the Longines Global Champions Tour and Global Champions League.
But despite being undoubtedly one of the most skilled riders on the tour, he couldn't have done it without the horse beneath him: Don VHP Z.
"He's a horse who needs a leader because otherwise he tells you how it's going to be," Smolders tells CNN.
"To perform well he needs to have a respect for the rider. Then he's very manageable and he's the same every day, which is probably his biggest quality."
The pair joined forces around three years ago, though Smolders admits the 14-year-old stallion only began to show his potential within the past 24 months.
"Don had a very good year last year," he recalls. "I think the last two years he's been very consistent, he's one of the best horses in the world at the moment.
"He's very consistent, he's very careful and he's very manageable."
Smolders believes Don's complicated nature made the start of their partnership tricky, but the pair have since created a powerful bond.
"I think we developed a relationship," he says. "It probably took us about a year before I figured him out and before I knew what he liked.
"I think at the highest level you need to know each other very well to make the difference. He knows what his job is and he really feels the atmosphere of the show. He can really enjoy a good performance."