"For sure I speak English good"

Once again this weekend, watching interviews with foreign F1 drivers and Wimbledon tennis stars for whom English is a second language, I was struck by how often they say “for sure”, often at the beginning of a sentence. Where does this idiom come from? It doesn’t seem to matter what their first language is. I am not conscious of native speakers using it very often, except for James Allen, a UK F1 commentator who has started using it which grates on me in a way foreigners using it never would.

Yeah I know what you mean.

Typical Valentino Rossi (MotoGP) speech goes something like:

“For sure, it was difficult. But. It was a great race. Casey was very fast. I see it is possible to win. I push and I am faster. So I win.”

I have no idea where it comes from.