Two-time Major winner Jordan Spieth has praised fellow American Dustin Johnson after his first round at The Open.

The duo are in a group together for the first two rounds at St Andrews and they both put themselves in good first-round positions, with Johnson taking the early lead at seven-under-par and Spieth not far behind on five-under.

Spieth and Johnson also went toe to toe at last month's US Open at Chambers Bay, where Spieth came out on top to win back-to-back Majors as Johnson three-putted the final hole.

Speaking to reporters after his first round at St Andrews, Spieth said: "I am very pleased with the start. It was certainly nice to finish [with a birdie]."

"If Dustin keeps driving the way he is I'm going to have to be at my best to have a chance. He doesn't really play badly, ever."

If Spieth wins this week, he will overtake Rory McIlroy to become world number one for the first time and also become the first man ever to win the first three Majors in a calendar year.