The Pebble Beach Pro-Am appears headed for a Monday finish after a hailstorm halted play in the final round on Sunday.

The late-morning hail quickly covered the greens and gave officials no choice but to suspend play, even before the leaders had teed off in northern California.

Play finally resumed more than two hours later at 1pm local time [9pm Irish], which meant the leaders would likely complete about 15 holes before darkness.

Englishman Paul Casey started the round at 15-under, three strokes clear of Phil Mickelson. Thirteen of Mickelson's 43 PGA Tour victories have come in his home state of California.

With a victory, he would match Mark O'Meara's record of five victories in the storied Pebble Beach event, which dates back to 1937 when it was won by Sam Snead. O'Meara was champion in 1985, 1989, 1990, 1992 and 1997. 

Northern Ireland's Graeme McDowell was nine-under through five.