Russell Knox laments 'horrendous' Sunday in WGC Shanghai defence
Defending champion Russell Knox "completely lost it" during the final round to fall away in the WGC-HSBC Champions event in Shanghai, China.
The Scot carded a two-over-par 74 on Sunday to finish eleven shots behind Japanese winner Hideki Matsuyama.
Knox, 31, had been second, three adrift of Matsuyama, after the third round.
"I definitely didn't play well enough to win today, so hats off to Hideki; he was brilliant," said Knox, who finished in a tie for ninth place.
Matsuyama hit six birdies in a flawless round of 66 to finish on 23 under par, seven shots clear of Sweden's Henrik Stenson and American Daniel Berger.
"Today was a bummer," said Knox. "I got off to an OK start but I was in between clubs a lot and I wasn't able to make birdies.
"I started to kind of force it - made a mistake, a bad swing - and before I knew it I'd made four bogeys in a row and I'd completely lost it.
"It was tough to pull myself back. I battled hard but it wasn't meant to be."
Knox, from Inverness, also carded a 74 last Sunday to finish in a tie for 10th at the CIMB Classic in Kuala Lumpur, Malaysia.
"Tied for ninth is never bad, but I should have done better than I did," he added.
"One of my goals was to have more top tens, so two out of two for the new season is not bad.
"I'm proud of that, just disappointed to play horrendous on the Sunday both times."
Matsuyama, 24, became the first player from Asia to win a World Golf Championships event and Knox was full of praise for his weekend playing partner.
"There were no weaknesses the last two days," he said. "He made it look very easy."