It was a day to forget in Shanghai for Roger Federer on Saturday as he went down in straight sets to Borna Coric. Photo: Andy Wong/AP

SHANGHAI – Roger Federer was turfed out of the Shanghai Masters semi-finals on Saturday by 13th-seeded Borna Coric, the Croatian stunning the Swiss great 6-4 6-4.

The 21-year-old Coric will face Novak Djokovic in Sunday’s final after the Serb thrashed Alexander Zverev 6-2 6-1, leapfrogging Federer to number two in the world rankings.

The 20-time Grand Slam champion Federer has not been at his brilliant best all week, dropping sets in the two opening matches of his wobbly title defence.

The 37-year-old top seed was more like his old self on Friday, defeating eighth seed Kei Nishikori of Japan 6-4 7-6 (7/4).

But he made a slow start against Coric, ranked 19 in the world, getting broken in the first game in an error-strewn performance.

There was a subtle shake of the head when Federer similarly lost his serve at the start of the second set.

“I thought he was better, I think he had more punch on the ball. He served better,” said Federer, proclaiming himself pleased overall with his form.

“I feel like I’m explosive out there, returning well. Serving, I think, it’s okay, could be even a little bit better.

“I don’t think I played a match where I didn’t get broken, so that’s something a bit more unusual for me.”

In contrast, Coric – who is into his first Masters 1000 final – was largely untroubled on his serve.

Remember the name.

Absolute perfection from @borna_coric 👏

Watch the @SH_RolexMasters live on @TennisTV 📺

— ATP World Tour (@ATPWorldTour) October 13, 2018

Federer won the Australian Open at the start of this year, but has had a mediocre season by his sky-high standards.

He exited the US Open in the last 16 at the hands of unheralded Australian John Millman, ranked 55th, and only made the quarter-finals at Wimbledon.

Coric, who has only two career titles to his name, has now beaten Federer twice – the previous time was in the final at Halle this year.

Coric's Maiden Masters 1000 Final 💪

Borna Coric stuns Roger Federer 6-4, 6-4 to book a final meeting with @DjokerNole in Shanghai. 🇨🇳


— ATP World Tour (@ATPWorldTour) October 13, 2018