Masters winner Bubba Watson adjusting his green jacket in Augusta.

Bubba Watson withstood an inspired early challenge from playing partner Jordan Spieth to clinch the Masters for a second time in three years with a three-shot victory at Augusta National on Sunday.

Trailing the prodigiously talented Spieth by two strokes after seven holes, the left-handed Watson took advantage of a faltering run by his fellow American around the turn as he upped his own game, then maintained control on the back nine.

Fan favourite Watson, who landed his first major title with a thrilling play-off win over South African Louis Oosthuizen in 2012, mixed five birdies with two bogeys to card a three-under-par 69 on a warm but mainly overcast afternoon.

The 35-year-old from Florida covered the back nine in even par to post an eight-under total of 280.

After being warmly embraced by his caddie, Watson shook hands with Spieth before he was then congratulated greenside by his wife Angie and their two-year-old boy Caleb.

Spieth, at 20 aiming to eclipse Tiger Woods by becoming the youngest player to win the Masters, had to settle for a share of second place at five under after signing off with a 72, finishing level with Swede Jonas Blixt (71).