While Don is 11th in the standings, Clarke is second, helped by his first-ever podium finish when he was runner-up in Hamburg last month.
"I was really surprised to get second," said Clarke. "I'm as fit [now] as I was in Hamburg - maybe even a bit fitter.
"[This race] counts heavily towards my world ranking. They're all important races, but this one especially. I need to get it right."
He has been training in Lanzarote ahead of the contest but the conditions have not suited him. "It's probably not the best place to train," Clarke said, "because it's so windy and hot."
But he is excited by the prospect of the home support this weekend. "It will be incredible," Clarke added. "Hopefully they'll all be out shouting our names. It [the home crowd] is definitely worth 10-15 seconds to us.
"It's motivating to have someone on a corner let alone every metre. You know they're all cheering for you. And I will try and pick out my family and friends. Whenever I see them I make an extra effort."
Despite his qualification for the Games still in the balance, Clarke issued this statement which will doubtless please British supporters and coaches alike. "Anyone that makes the Great Britain team can get a medal," he said.
Will Clarke is an ambassador for Multipower sports food. For sports nutrition tailored to your individual needs visit multipoweruk.com
