Nuneaton's Andy Sullivan, who played Jordan Spieth in the 2011 Walker Cup, says St Andrews will be "a different challenge" for this year's twice major champion.
Spieth, 21, has won both the US Masters and US Open so far in 2015.
"The Open is going to be a different challenge to Chambers Bay and the Masters," Sullivan told BBC Midlands Today.
"The weather is going to be a factor. It's more unpredictable in Scotland. If he wins that one too, you'd fancy him to go and do the Grand Slam but there'll be a lot of players looking to take it away from him."