Runner-up Spieth laments 'dumb mistakes' that cost him

Runner-up Jordan Spieth was left to contemplate what might have been after a "couple of really dumb mistakes" thwarted his chances of a second Open Championship title.

The American shot an impressive final round of 66 at Royal St George's on Sunday to finish two shots behind compatriot Collin Morikawa.

But by then Spieth, the 2017 Open champion, had seen his hopes of a fourth major title upended on Saturday when he completed his third round with consecutive bogeys.

"The finish yesterday, was about as upset as I've taken a finish of a round to the house," Spieth said on Sunday.

"I walked in and wanted to -- I said, 'Is there something that I can break?'

"I knew that was so important because I would have been in the final group."

That poor finish to his third round meant Spieth had to tee off ahead of Morikawa, who was paired with overnight leader Louis Oosthuizen.

Spieth, who started the day on nine under par, three shots behind South Africa's Oosthuizen, did not help his own cause by dropping two shots in the first six holes.

He rallied by completing the final 12 in six under par but, with Morikawa, three years his junior at 24, holding firm, Spieth never really threatened to end a four-year wait for a fourth major title.

"I had to regroup 18 hours later and then just had a lot in between clubs, and you have to be so precise here," Spieth said.

"Then I kind of fatted it off six and went to seven thinking, 'Okay, now we're going for everything, and we're going to see what happens'.

"I'm proud of going 6-under in the last 12 in this golf tournament and putting some pressure on Collin."

Spieth added: "I needed a break, and I didn't get it from him. I did all I could.

"So I'm upset because I really felt like I played well enough to win and made a couple of really dumb mistakes that possibly, if I had maybe played the week before, wouldn't have made -- like just stepping in and missing a couple footer (putt) on 18 yesterday (Saturday), not really thinking about it.

"But at the same time, I did everything I could in the past few hours to win this championship."